The row between the UK and Scottish government over the preparations for the COP26 Summit in Glasgow show few signs of abating, after Number 10 issued a thinly veiled warning that the venue had to deliver "value for the UK taxpayer".

Asked yesterday about reports the government was in talks with the ExCel London centre as a potential alternative venue for the Glasgow Summit, a spokesman for Number 10 told reporters that it was "standard practice to carry out contingency planning for major international events at this scale".

But he also indicated that there were budgetary considerations the Glasgow venue would have to meet. "We are committed to holding COP 26 in Glasgow, but the Scottish government needs to work with us to make sure this is a successful summit, which showcases the UK as a world leader in tackling climate change and represents value for the UK taxpayer," he was quoted as saying.

Earlier this week both Cabinet Secretary Michael Gove and Scottish First Minister Nicola Sturgeon called for the two governments to work together to ensure the Summit is a success.

But tensions between Westminster and Holyrood are said to be running high over the estimated cost of policing the summit and the allocation of venues near the main UN site.

With speculation growing that the government could yet move the venue to London, Sturgeon accused Johnson of "playing politics with the biggest issue of our time".

Meanwhile, Johnson is expected to soon name a new President for the Summit following the sacking nearly two weeks ago of Claire O'Neill. Gove had been hotly tipped to the take the role, but refused to drawn on whether he wanted the post at an event this week. The Guardian reported that government sources had suggested the job could be considered too onerous to add to his already extensive list of responsibilities.

At the same time preparations for the Summit are continuing. The official COP26 Twitter account announced yesterday that the government was "delighted to welcome the @UNFCCC team to Glasgow & London this week for their first technical mission ahead of #COP26".

Delighted to welcome 🤝 the @UNFCCC team to Glasgow & London this week for their first technical mission ahead of 🇬🇧 #COP26.

Their visit is part of extensive preparations to ensure that the summit delivers on its potential 💚 and is where the 🌍 agrees ambitious #ClimateAction. pic.twitter.com/DPQgWYadQ7

— COP26 (@COP26) February 12, 2020

It also revealed that the Post Office is to produce a new post mark for letters to promote COP26 and the government's 'Year of Climate Action'.

Separately, Environment and International Development Minister Zac Goldsmith - who has also been tipped as a prospective COP26 Summit - announced that the Department for International Development was working on plans to work with developing countries to lead a crackdown on illegal logging and timber exports.

The hope is to form a new international alliance to combat illegal timber and deforestation that can help drive progress at the COP26 Summit.

"The illegal timber trade robs the earth of trees, which not only help stop climate change, they also play a critically important role in maintaining the world's threatened biodiversity," said Goldsmith. "This is a huge success story for the UK and for the world, and sets the scene for what we hope will be a successful year of international cooperation in the run-up to COP 26."

The latest developments come as political opponents continue to crank up the pressure on the government to beef up its preparations for the crucial Summit and strengthen domestic decarbonisation policies.

Acting Lib Dem leader Ed Davey is today set to deliver a speech in which he will call for the creation of a cross-party committee of MPs, campaigners, business figures, and climate experts to advise the government on how best to deliver a successful Summit.

"We need NGOs, politicians and business leaders to form a committee to help to reach greater dialogue on international action," he told the Guardian, adding that the preparations thus far for the Summit had been "shambolic". "Insiders are tearing their hair out," he added. "If you want to be credible hosts, you have to engage with people, with society, with NGOs far more."   

The comments came as Energy Minister Kwasi Kwarteng sought to reassure a meeting of the International Energy Agency (IEA) that hosting a successful Summit was the top priority for the government.

"We can't guarantee success, it's not something we can gold-plate, but this is absolutely our No 1 priority as a government," he said. "We really cannot afford it to be a failure, at an international level and at a national level, given where we are with Brexit and other issues."