The Gambia's opposition coalition has called on President Yahya Jammeh to step down immediately, after he challenged his defeat in the recent election.

Mr Jammeh initially accept the result but then reversed his decision and said he would annul the election.

His party says it would file a petition to the Supreme Court.

The UN and the African Union have called on Mr Jammeh to respect the election verdict.

Several West African leaders are to fly to The Gambia's capital, Banjul on Tuesday to try and resolve the political crisis.

"I think he should step down now," said Adama Barrow, who was declared the election winner.

"He has lost the election, we don't want to waste time, we want this country to start moving," he told the AFP news agency.

President Jammeh went on national TV over the weekend to announce his "total rejection of the election result... thereby annulling the election".

He said "we will go back to the polls because I want to make sure every Gambian has voted".

He said he was preparing a petition "against the flawed decision of the Independent Elections Commission".

Adding errors

According to the electoral commission's latest count, as a result of the vote on 1 December:

• Adama Barrow won 222,708 votes (43.3%)

• President Jammeh took 208,487 (39.6%)

• A third-party candidate, Mama Kandeh, won 89,768 (17.1%)

They were revised by the country's electoral commission on 5 December, when it emerged that the ballots for one area had been added incorrectly, swelling Mr Barrow's vote.

The error, which also added votes to the other candidates, "has not changed the status quo" of the result, the commission said.

However, it narrowed Mr Barrow's margin of victory from 9% to 4%.

Mr Jammeh, who has ruled the Gambia for 22 years, originally conceded victory to Mr Barrow, who used to be a security guard in chain store Argos in London.

He was even shown telephoning Mr Barrow saying "you are the elected president of Gambia and I wish you all the best".

Last week a leading member of Mr Barrow's coalition told the UK's The Guardian newspaper that President Jammeh would be prosecuted for alleged crimes committed during his rule.

In his U-turn rejecting the results, Mr Jammeh cited "serious and unacceptable abnormalities" in the electoral process, pointing to the errors mentioned by the electoral commission.

Despite the errors, election commission head Alieu Momarr Njai told Reuters news agency that he stood by the "if it goes to court, we can prove every vote cast".

"The election results were correct, nothing will change that," he said.

President-elect Barrow said on Sunday that he feared for his safety.

In his 22 years in power, Mr Jammeh acquired a reputation as a ruthless leader.

Human rights group have accused his government of stifling the press and harassing opposition parties.