Russia, Namibia and the Seychelles are being added to the “red” list, government spokesman Gabriel Attal told reporters on Wednesday.

Russia, and especially Moscow, have been hard hit by the highly infectious Delta variant first identified in India in recent weeks, a problem compounded by slow take-up of vaccines even though the country has produced its own jabs.

The Delta variant is also causing concern in the UK, where is now accounts for 90 percent of all cases.

Asked if France was considering adding the UK to its red list, Attal said: “We adapt our rules according to the development of the threat. If measures  need to be taken for other countries, then we will take them. But at this stage I have no information to communicate.”

As it seeks to stop the spread of potentially dangerous variants in the face of an increasingly successful vaccination programme, France has divided the world into green, orange and red countries for travel and imposed more relaxed rules for fully-vaccinated travellers.

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Travellers from red list countries can only come to France for essential reasons and even fully vaccinated travellers who meet the vital reasons criteria must quarantine for 7 days on arrival.

Unvaccinated travellers who meet the vital reasons criteria must quarantine for 10 days – the quarantine can be done in a private home, but is enforced by visits from the police.

There has been concern over the rise of Delta variant cases in the UK. The recent spike in cases there has been far less drastic than in Russia against the background of the rapid vaccination rollout in the UK, where 82 percent of adults have had at least one jab.

Still hospitalisations and the numbers of patients on mechanical ventilators, while well down from their peak, have crept up in recent weeks.

There were 227 people on a ventilator on June 21st, up from 120 a month earlier, NHS data show.