The British Foreign Office says "large numbers" of Britons are still stuck abroad due to volcanic ash but the true figure is very hard to quantify.
It said trouble spots included Hong Kong, Pakistan, Thailand and Orlando, Florida, but the situation was easing.
The Association of British Travel Agents said the majority who had booked with its operators were now home.
But it said those awaiting chartered flights could take a few more days and those on scheduled flights even longer.
On Sunday, the BBC reports, the association said about 35,000 Britons had booked with travel operators but were yet to board flights at airports around the world.
Flight restrictions imposed two weeks ago because of ash from the Eyjafjallajokull volcano in Iceland have been lifted.