West African leaders are in The Gambia to try to persuade Yahya Jammeh to cede power to his elected successor.
Mr Jammeh has asked for the deadline for him to leave office or be forced out by UN-backed forces to be extended until 16:00GMT on Friday.
Mr Jammeh had been given until noon. The presidents of Guinea and Mauritania have arrived for last-minute talks.
Troops, which crossed from Senegal on Thursday, have been told to halt their advance until the talks are over.
The Economic Community of West African States (Ecowas) is acting in support of new President Adama Barrow, who was sworn in at a ceremony in The Gambia’s embassy in Senegal on Thursday.
Mr Barrow’s legitimacy as president has been recognised internationally, after he won last month’s elections.
Guinea’s President Alpha Conde and Mauritanian President Mohamed Ould Abdel Aziz arrived in Banjul on Friday morning for the talks with Mr Jammeh.
The chairman of the Ecowas commission, Marcel Alain de Souza, said that if the meeting with Mr Conde proved unsuccessful, military action would follow.
Ecowas said that its forces had encountered no resistance after entering The Gambia.
The troops are from Senegal and other West African countries.
Mr Barrow, who remains in Senegal, has said that he will not return to Gambia’s capital, Banjul, until the military operation has ended.
The threat by the West African regional bloc Ecowas to remove Mr Jammeh by force is supported by the 15-member UN Security Council, although the council has stressed that a political solution should be the priority.
A Senegalese army spokesman, Col Abdou Ndiaye, told the BBC that troops who were now in The Gambia were prepared to fight if necessary.
“It is already war, if we find any resistance, we will fight it,” he said, adding: “If there are people who are fighting for the former president, we will fight them.”
But Col Ndiaye said the main goal of Ecowas was to restore democracy and to allow the newly-elected president to take power.
In his inaugural speech at the Gambian embassy in Senegal’s capital, Dakar, President Barrow ordered all members of The Gambia’s armed forces to remain in their barracks.
Any found illegally bearing arms would be considered “rebels”, he said.
Amid the crisis, the UN refugee agency reported that more than 45,000 people had fled The Gambia for Senegal so far this year.
More people could leave if the situation was not resolved, the UNHCR said. BBC News