The top UN official in West Africa said on Wednesday that Gambian President Yahya Jammeh will face strong sanctions if he refuses to step down after his elected term ends next month according to Reuters.

Jammeh came to power in 1994 in a coup. His 22-year presidency has been criticized by detractors as autocratic and having many human rights violations.

The Gambian president had conceded defeat in the December 1 election to Adama Barrow.

He has since rejected the election results, which his party is disputing in the Gambian Supreme Court.

“For Mr. Jammeh, the end is here and under no circumstances can he continue to be president. By that time (Jan. 18), his mandate is up and he will be required to hand over to Mr. Barrow,” Mohammed Ibn Chambas, U.N. Special Representative for West Africa and the Sahel, told Reuters.

He said Jammeh would be “strongly sanctioned” if he refused to leave office.

Reuters reported that Chambas and a delegation of presidents representing the Economic Community of West African States (ECOWAS) attempted to reach a deal with Jammeh so he would relinquish the presidency.

Negotiations failed when Gambian soldiers seized the headquarters of the national elections commission, preventing the delegation from entering.

On Wednesday, United Nations Secretary-General Ban Ki-moon said that this act was an “outrageous act of disrespect of the will of the Gambian people”.

No one has been able to enter the building in the capital Banjul aside from two armed guards. All entrances to the building are closed.

“No one has gone to work. I didn’t even try. No one has informed me that I can go back,” elections commission chairman Alieu Momarr Njai said on Wednesday.

The ruling Alliance for Patriotic Reorientation and Construction filed to challenge to the election result during the delegation’s mediation meetings on Tuesday.

The court has not been in session for a year and a half.

Legal experts suspect that the court needs at least four new judges before it can hear Jammeh’s petition.

“We do not believe it will be heard by a credible court dedicated to ensuring the integrity of The Gambia’s democratic process,” a U.S. Embassy statement said.

If the UN does not agree with the Supreme Court’s decision, it may intervene.

In 2010, UN troops took military action to remove Ivory Coast’s former president, Laurent Gbagbo when the constitutional court overturned the election victory of Alassane Ouattara.

When asked if international forces would become military involved in Gambia, Chambas stated, “It may not be necessary. Let’s cross that bridge when we get there.”

ECOWAS leaders will discuss the situation in Gambia at a summit in Nigeria on Saturday.