The UN Security Council will on Monday hold a closed-door meeting on the crisis in Gambia to press demands for a handover of power by longtime leader Yahya Jammeh following elections, diplomats said.

Senegal, a non-permanent council member, requested the consultations scheduled for midday (1700 GMT).

UN West Africa envoy Mohamed Ibn Chambas, Nigerian President Muhammadu Buhari and Liberian leader Ellen Johnson Sirleaf in her capacity as head of the west African ECOWAS bloc are set to arrive in Banjul on Tuesday to try to persuade Jammeh to step down.

The Security Council on Saturday released a unanimous statement demanding that Jammeh "transfer, without condition and undue delay, power to President-elect Adama Barrow."

Jammeh, who has been in power for 22 years, accepted defeat a day after the December 1 vote, but backtracked on Friday, saying he rejected the election results and calling for a new vote.