BANJUL (Reuters) - Gambia’s President-elect Adama Barrow said on Saturday that outgoing leader Yahya Jammeh had no authority to reject the results of the Dec. 1 election, while the United Nations and African Union piled pressure on Jammeh to step aside.

Gambian President Yahya Jammeh leaves a polling station with his wife Zineb during the presidential election in Banjul, Gambia. REUTERS/Thierry Gouegnon

Long-ruling Jammeh had conceded defeat publicly last week after his narrow loss to opposition leader Barrow.

But on Friday he called for another election in the tiny West African country, jeopardizing what was expected to be Gambia’s first democratic transition of power in more than 50 years.

The announcement on state television threw the future of the country of 1.8 million into doubt. The surprise election result that ended Jammeh’s authoritarian 22-year rule had been widely seen as a moment of democratic hope and a chance to end repression in a country known as a police state.

“The outgoing president has no constitutional authority to reject the result of the election and order for fresh elections to be held,” Barrow told reporters in Banjul.

“I open up a channel of communication to convince him to facilitate a smooth transfer of executive powers in the supreme interest of this country,” he said.

Outside Barrow’s house, which over the last week had become a gathering point for revelers, about 20 people sitting on plastic chairs said they had volunteered to provide security.

None were armed.

“The way Jammeh is speaking it sounds threatening,” said one volunteer, Jadama Ibrahim, wearing tracksuit bottoms and slippers. “He (Barrow) was relocated twice. We are concerned about his safety.”

The streets of Banjul were calm on Saturday with a strong police presence.

International criticism of Jammeh came in fast. Following the United States and Senegal, the African Union on Saturday weighed in, calling Jammeh’s statement “null and void”. The European Union has also called for a peaceful transfer of power.

Senegal, which has Gambia’s only land border and once sent troops there during a coup, has called for an emergency meeting of the U.N. Security Council and “solemnly” warned Jammeh not to harm Senegal’s interests or its citizens in Gambia.

But in a sign that early mediation efforts may be floundering, Senegal’s Foreign Minister Mankeur Ndiaye told Reuters that Gambian authorities had refused entry to the chair of regional body ECOWAS.

“Johnson Sirleaf was supposed to fly in today, but Jammeh said ‘not at the moment,’” he said.

It was not clear if the plane had already taken off. Liberian officials could not be reached for comment.

The 15-member U.N. Security Council on Saturday condemned the latest statement from Jammeh and called for him to transfer power “without condition and undue delay”. They intend to review the situation on Monday before deciding whether to hold a meeting, diplomats said.

The U.N. and regional body ECOWAS called on the armed forces to stay neutral.

Barrow aides say the head of the army has pledged support to him but Gambians have voiced private concerns that a faction from Jammeh’s Jola ethnic minority might protect him, potentially provoking broader conflict along ethnic lines.

Jammeh also said in his speech on Friday that he would not tolerate protests in what Amnesty International called an “extremely dangerous move that risks leading to instability and possible repression”.

Under chapter 5 of Gambia’s constitution, candidates have 10 days from the declaration of results to appeal to the Supreme Court. It was not immediately clear if Jammeh had done that, and Gambia’s Information Minister could not be reached.

His objections to the poll results follows a correction by the Independent Electoral Commission this week which gave Barrow a much slimmer final victory margin of fewer than 20,000 votes.

In a sign of the determination of some Barrow supporters to uphold the poll outcome, the website of Gambia’s presidency was hacked and showed a picture of a smiling Barrow.

“The struggle continues, victory is certain,” the State House website said, quoting in Portuguese the rallying cry of Mozambique fighters during their war for independence.

A third party candidate in last week’s election, Mama Kandeh of the Gambia Democratic Congress also rejected Jammeh’s call for another election.

“Your swift decision earlier to concede defeat and your subsequent move to call Adama Barrow to congratulate him was lauded throughout the world,” Kandeh said. “We therefore prevail on you to reconsider your decision.”