Coronavirus: What are the UK's travel rules and which countries can you visit?

Quarantine restrictions have been reintroduced for people entering the UK from Croatia, Austria and Trinidad and Tobago from 04:00 BST on Saturday. Travellers from Switzerland to Scotland will also have to self-isolate.

Those arriving from several other countries, including France and Spain, have also been told to self-isolate on arrival, although people coming to the UK from Portugal no longer have to quarantine from Saturday morning.

The decision is triggered when a country's rate of infection exceeds 20 cases per 100,000 people over seven days.

The Joint Biosecurity Centre (JBS) - set up by the government to monitor coronavirus - advises which countries should be on the quarantine list, and which should be exempt.

It considers:

In June, a two-week quarantine was brought in for most people entering the UK from overseas.

In July, the government published a list of more than 50 countries exempted from the rules because of their lower coronavirus rates.

But quarantine restrictions have been reapplied to several countries since then:

The decision that travellers from Croatia, Austria, Trinidad and Tobago would have to go into quarantine followed a "significant change in both the level and pace of confirmed cases", the Department for Transport said.

The weekly incidence of cases per 100,000 in Croatia increased from 10.4 on 12 August to 27.4 on 19 August. In the seven days up to 20 August in Austria, cases per 100,000 went up from 10.5 to 20.3. And in Trinidad and Tobago, there has been a consistent rise over the past four weeks.

In Luxembourg and Belgium, which have been removed from the list, two-week rates per 100,000 people stand at 122.5 and 58.7 respectively.

The list is kept under constant review, and the government says it ''will not hesitate'' to remove more countries if conditions worsen.

Travellers are exempt from quarantine if they arrive in England, Wales and Northern Ireland from countries that - according to the government - pose a "reduced risk" from coronavirus.

Brunei and Malaysia were added to the exemptions list at 04:00 BST on 11 August.

It also includes:

Those entering the UK from the common travel area - the Republic of Ireland, the Channel Islands, or the Isle of Man - are exempt, as are the 14 British Overseas Territories.

Health measures like quarantine are set by each UK nation separately.

Wales and Northern Ireland have introduced quarantine exemptions for the same countries as England. Scotland is also allowing exemptions, and has updated its own list of countries with which it is now allowing travel without quarantine.

You must isolate for 14 days if you arrive in the UK from Canada, the US, much of Central and South America, and some countries in Africa, the Middle East and Asia.

Travellers from Sweden, Russia and anywhere else not on the list also have to quarantine.

Further restrictions may also be placed on UK travellers if its infection rate rises.

Travellers leaving the UK could still face restrictions - including quarantine - when they arrive in one of the exempted countries.

About half the countries and territories on the list have restrictions for arriving UK visitors. These include: