The US State Department has added the UK to its “Level Four: Do Not Travel” advisory list, citing a “very high level of COVID-19" as its reasoning.

The UK is among at least 116 countries, including; Canada, France, Israel, Mexico, Germany and others, that now have the strongest advisory rating.

Earlier this week, the State Department said there would be a rise in the number of countries receiving its highest advisory rating to about 80% of countries worldwide.

The change in the warning level for the UK began on Tuesday.

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A statement on the US Government travel website says: "Do not travel to the United Kingdom due to COVID-19.

"The Centers for Disease Control and Prevention (CDC) has issued a Level 4 Travel Health Notice for the United Kingdom due to COVID-19, indicating a very high level of COVID-19 in the country.

"There are restrictions in place affecting U.S. citizen entry into the United Kingdom."

The new travel advisory has thrown into question whether there will be a US-UK travel corridor this summer.

Just this week UK transport secretary Grant Shapps said he was having "regular" talks with his US counterpart at an Airlines UK webinar.

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The State Department said the move did not imply a reassessment of current health situations in some countries, but rather “reflects an adjustment in the State Department’s Travel Advisory system to rely more on (the U.S. Centers for Disease Control and Prevention’s) existing epidemiological assessments.”