The carrier has suspended regular flights until 30 April, but is operating selected special services to repatriate visitors.

Limited commercial flight options otherwise remain for Britons seeking to return from the island nation, according to the Foreign Office (FCO) – which has confirmed the Saturday flight.

However, the FCO will not operate dedicated rescue charters until all commercial options are exhausted, and has urged any Britons still in Sri Lanka to return home by commercial means if possible.

"Sri Lankan Airlines have extended the suspension of regular flights until at least 30 April," said the FCO, which updated its travel advice for Sri Lanka during the early hours of Wednesday morning (15 April).

"However, they will operate a special flight (UL503) from Colombo to London on 18 April. Sri Lankan Airlines have confirmed that seats are available on this special flight.

"Qatar Airways services have been reduced to one flight per day to Doha, with onward connections to the UK. The airline tell us that they intend to keep operating this route for as long as possible. We are unable to say how long that might be."

The new FCO advice adds: "Airlines operating via the United Arab Emirates, including Emirates and Etihad, have suspended flights out of Colombo indefinitely.

"Some airlines are changing flight schedules with little prior notice. You should keep in close contact with your airline or travel agent."

The FCO has, meanwhile, convened a rescue flight from Nepal, which will operate on Friday (17 April) from capital Kathmandu.