Thousands of people have begun fleeing Gambia amid growing signs that West African states could invade the former British colony within days.

Regional leaders have signalled their determination to mount a rare African defence of democratic principle by using force to ensure that Yahya Jammeh, Gambia’s president of 22 years, gives up power following his defeat in an election last month.

Nigeria has reportedly asked British military advisers to assist in planning a “rapid reaction” military incursion into Gambia in order to install Adama Barrow, the election’s surprise winner, as the country’s new president.

Mr Barrow, a former real estate agent who briefly worked as a security guard at an Argos catalogue store while studying in London, was supposed to have been sworn in on Thursday — but Mr Jammeh, having initially conceded defeat, later reversed course and is refusing to stand down.

Mr Barrow left Gambia for neighbouring Senegal at the weekend at the advice of regional leaders, and will not return home until his inauguration until Thursday - perhaps under the escort of West African troops.

The president-elect's inauguration plans were struck by tragedy after his son Habibu, who was eight, died on the way to hospital on Sunday after being bitten by a dog the previous evening near the capital Banjul, according to the BBC and postings by Gambians on Twitter.