Britons travelling abroad should return to the UK as soon as possible, the Foreign and Commonwealth Office (FCO) has warned.
In its latest travel advice, the government department urges all British tourists and short-stay travellers to come home while commercial flights are still available.
Further closures to air routes may be enforced within the next 48 hours, possibly without notice, the FCO stressed.
Some Brits are already experiencing travel issues owing to restrictions imposed by individual countries around the world.
But the foreign office insists it is working “around the clock” to support those stranded abroad, including by negotiating with airlines to keep routes open.
Foreign Secretary Dominic Raab said: “We are strongly urging UK travellers overseas to return home now where and while there are still commercial routes to do so.
“Around the world, more airlines are suspending flights and more airports are closing, some without any notice.
“Where commercial routes don’t exist, our staff are working round the clock to give advice and support to UK nationals.
“If you are on holiday abroad the time to come home is now while you still can.”