The Foreign Office has warned against all but essential travel to Sri Lanka following the Easter Sunday bombings.
Foreign Secretary Jeremy Hunt said: "Our hope is that it will be possible to change this when the current security operation has concluded.
"My first priority will always be the security of British citizens living and travelling abroad."
UK travellers in Sri Lanka or with future bookings are being urged to contact their airline, tour operator and insurer after the Foreign Office advised against all but essential travel to the island.
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Travel trade organisation Abta said customers due to travel to the island "imminently" for a package holiday would be offered a postponement, a full refund or a holiday in an alternative destination.
But anyone who booked their flights and accommodation separately will need to discuss their options with the individual companies.
Holidaymakers with travel insurance may be able to claim for losses depending on the terms of their policy.
An estimated 8,000 British tourists are in Sri Lanka.
The Foreign Office urged them to keep a low profile, avoid crowded public places and remain vigilant.
It is not yet known if travel companies will make special arrangements to bring travellers back to the UK earlier than planned.
Colombo Airport is continuing to operate but with increased security checks and long queues.
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It is unlikely there will be a repeat of the major airlift which was organised when commercial flights to and from Egypt's Sharm el-Sheikh Airport were banned in November 2015.
A spokeswoman for tour operator Tui said: "We have started to contact customers in resort and those who are due to travel in the next seven days to discuss changes to travel arrangements.
"The safety and security of our customers and staff remains our highest priority."
The Foreign Office travel advice is likely to have a major impact on Sri Lanka's tourism industry.
Annual tourism visits to the island have increased from fewer than half a million in 2009 to a record high of more than two million in 2017.
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