The Foreign and Commonwealth Office is warning against "all non-essential travel" to the west African nation due to potential military intervention following presidential elections on December 1.
There are fears the main international airport could be shut at short notice and holiday company Thomas Cook will lay on additional flights from the capital Banjul today to bring 985 package trip customers home.
The holiday firm said a flight scheduled from Manchester will leave the UK without passengers and bring the first group of tourists home. A further four flights have been arranged from Banjul back to the UK later - two flying to Manchester and two to Gatwick.
An additional 2,500 "flight-only" customers will then be contacted and offered the earliest possible flights back to the UK.
The action comes after Gambian President Yahya Jammeh declared a state of emergency after refusing to hand power to opposition leader Adama Barrow, who won last month's election.
Mr Jammeh, who has ruled The Gambia with an iron fist for 22 years, initially acknowledged Mr Barrow as the winner but later said the ballot count was flawed and lodged a complaint with the country's supreme court.
State television said the state of emergency would prevent a power vacuum while the court rules on Mr Jammeh's petition challenging the election result.
Regional leaders have threatened to intervene with military force if Mr Jammeh does not step down by a deadline later this week.
The Association of British Travel Agents estimates there are around 2,000 people on holiday with its members in The Gambia and more will have travelled there independently.
British tourists on package holidays in the country were told to contact their tour operator to arrange return flights and independent travellers should contact their airlines.
An FCO spokesman said: "The potential for military intervention and civil disturbance is high and could result in Banjul International Airport being closed at short notice."
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