All the investigations facing the government, explained

A number of probes are under way into the conduct of government ministers past and present, with most focused on the prime minister himself.

All involved deny any wrongdoing. Here is a rundown of the main investigations.

Boris Johnson is facing questions over how the refurbishment of his official flat in Downing Street was paid for.

The prime minster says he has covered the costs himself - and insists he has obeyed the code governing ministers' behaviour.

But despite repeated questioning, he has not specified who paid the initial bill and whether it was a Conservative party donor, as has been reported. Several inquiries are seeking to find out.

What's the probe about?

The watchdog is examining whether the Conservative Party has breached laws on political finance. It follows claims that the costs of refurbishing the Downing Street flat could have been initially covered by undeclared donations.

Under the rules, parties are supposed to report donations to the commission if they are above a certain amount. The party has said it believes all reportable donations have been correctly declared.

What are the terms of reference?

It has powers to require parties, and any relevant individuals, to hand over documents and attend interviews to provide information. If it discovers a potential breach that would exceed its punishment powers, it can refer the matter to the police.

What could happen?

Any finding that the Conservatives breached the law would be politically embarrassing for Mr Johnson. It could also prove expensive for the Conservative Party, because the commission can issue fines of up to £20,000 and ask the courts to make parties pay donations back.

What's the probe about?

Five months after the post became vacant, Mr Johnson has asked his newly-appointed adviser on ministerial standards, Lord Geidt, to look into the "facts surrounding" the flat revamp. Lord Geidt has said his report into the flat will be published by the end of May.

What are the terms of reference?

Lord Geidt is looking into whether Mr Johnson has any income or donations he needs to declare in the register of ministerial interests. The register is meant to protect against conflict of interests but it has not been updated since last July. Lord Geidt says he plans to sign off on the latest version by the end of May.

What could happen?

Lord Geidt can recommend that the PM make further declarations. However, Mr Johnson can decide whether or not to follow these recommendations.

Lord Geidt told MPs he was prepared to resign if his advice is ignored.

What's the probe about?

Cabinet Secretary Simon Case, the UK's top civil servant, says the PM has asked him to review how the renovations were paid for. In late April, he told MPs on the Commons public administration committee this should take a "matter of weeks," and he will share his findings with them.

What are the terms of reference?

Mr Case told the MPs he will look broadly at "how [the refurbishment] has been done". He mentioned two areas in particular: whether any donations would give donors undue influence over the prime minister, and making sure donations are properly declared.

What could happen?

As a civil servant, the cabinet secretary does not have powers to give sanctions or enforce his findings. But if he concludes the prime minister has acted improperly, it would cause Mr Johnson political embarrassment. Mr Case has also promised to tell MPs about the advice Mr Johnson was given by civil servants regarding the funding - which could open up lines of inquiry for other probes.

Mr Johnson has been facing questions about his relationship with American businesswoman Jennifer Arcuri while he was mayor of London between 2008 and 2016. Ms Arcuri received public grants for her technology business and event sponsorship, and was given access to three foreign trade missions led by Mr Johnson.

She has since claimed to have had an intimate relationship with Mr Johnson, raising questions about conflicts of interest. Mr Johnson has always denied wrongdoing.

The Independent Office for Police Conduct (IOPC) said last year it will not be carrying out a criminal investigation into his dealings with Ms Arcuri.

But he still faces an investigation by the London Assembly, which scrutinises the capital's mayor.

What is the probe about?

The assembly's 11-member Oversight Committee has an ongoing investigation into Mr Johnson's relationship with Ms Arcuri. It was paused during an investigation by the IOPC but is expected to resume.

What are the terms of reference?

The Labour assembly member who chairs the committee, Len Duvall, said that after the IOPC probe concluded, the committee would look at Mr Johnson's conduct as mayor, including whether he adhered to the "principles of public life".

What could happen?

Any finding that he acted improperly could be politically damaging, and embarrassing, for Mr Johnson. But as he is no longer mayor, the Assembly will not be able to impose any sanctions or question him further.

A row about lobbying began earlier this year after it emerged that former Conservative prime minister David Cameron bombarded ministers and officials with texts on behalf of finance firm Greensill Capital.

His unsuccessful attempts to help the company take part in a government-backed Covid loan scheme have led to scrutiny of lobbying practices.

Mr Cameron has insisted he had not broken any rules, but acknowledged it would be better for ex-PMs to communicate more formally with government figures, through letters rather than texts.

What is the probe about?

After Mr Cameron's lobbying activities were revealed in several newspaper reports, Boris Johnson announced a review into government decisions involving Greensill. It will be led by lawyer Nigel Boardman, who has stepped aside as a non-executive board member at the business department to conduct the review. He has been told to report his "findings and any recommendations" before the end of June.

What are the terms of reference?

The government has said Mr Boardman will look into the government's use of supply-chain finance, a financial technique in which Greensill specialised. The review will also examine the relationship between the firm and current and former ministers. It will also examine whether "relevant systems and policies" were upheld.

What could happen?

Mr Boardman will not have any legal powers, but the government has said he will have access to "all relevant documentation" and be allowed to interview "relevant individuals". Mr Boardman could find that current and former ministers have broken the rules, or that the rules themselves are not fit for purpose. It would then be up to the government to decide what action to take.

Three Commons select committees have also launched inquiries into Greensill:

David Cameron insisted his lobbying for Greensill was in the public interest, but also revealed he was paid "far more" by the finance firm than he was as PM, during appearances before the Treasury committee and the Public Accounts committee.

There is also a review into second jobs held by senior civil servants, after it emerged the former chief officer for government procurement had worked for Greensill while still in his role.

And there is a National Audit Office investigation into how Greensill Capital was allowed to offer government-backed loans during the pandemic, months before it collapsed.

What is the probe about?

There's also an investigation into the funding of a 2019 holiday Boris Johnson took with his fiancee, Carrie Symonds, on the Caribbean island of Mustique. Mr Johnson has previously declared he received accommodation worth £15,000, covered by Carphone Warehouse co-founder David Ross.

But Mr Ross initially said he had not paid "any monies" for the trip. He later clarified that he had "facilitated" accommodation for the prime minister.

What are the terms of reference?

Commons standards commissioner Kathryn Stone has confirmed she is looking into whether the prime minister correctly declared how the trip was paid for in his MPs' register of interests. The commissioner normally investigates whether MPs have failed to declare a financial interest, not declared it correctly, or declared it late.

What could happen?

Ms Stone will report her findings to the Commons Standards committee, which can order MPs to apologise or pay back money if they are found in breach of the code.

In extreme cases it can recommend MPs are suspended, although this requires approval from the whole Commons and has only happened a handful of times. Mr Johnson's 80-strong majority makes his suspension even less likely.