Central African Republic leader Francois Bozize has said he is ready to form a national unity government with rebels, as they continue their advance towards the capital Bangui.
Mr Bozize's remarks came after a meeting with African Union chairman Thomas Boni Yayi.
He said he would hold peace talks with rebels in Gabon, and would step down when his term ended in 2016.
The rebels told the BBC they would consider the president's offer.
They had pledged to depose Mr Bozize unless he negotiated with them, but have also said that it is not their aim to enter government themselves.
Government troops have reportedly pulled back to Damara, 75km (48 miles) from the capital, in the face of a rebel advance, but rebel spokesman Eric Massi told the BBC they would not march on Bangui itself before seeing the outcome of the talks.
BBC Africa analyst Mary Harper says they are insisting that they do not want to take over, but rather are seeking a peaceful democratic transition.
But such a transition is unlikely, and meanwhile President Bozize is growing weaker both politically and militarily by the minute, she adds.
"I am ready to form a government of national unity with Seleka to run the country together, because I am a democrat," Mr Bozize said at a news conference after his meeting with Mr Boni Yayi, quoted by Reuters.
He said he was ready to attend the Gabon talks "without condition and without delay".
Earlier, the Seleka rebel alliance entered the central city of Sibut after the army withdrew on Friday evening.
More troops from the Central African Multinational Force (Fomac) arrived in CAR on Saturday to reinforce a contingent already there.
More than 100 French paratroopers have also been sent in. However, France insists they are only there to secure its nationals - not to save the regime.
A senior UN official told the BBC that all its international staff had been evacuated to neighbouring Cameroon.
The US has also evacuated its embassy in Bangui.
BBC West Africa correspondent Thomas Fessy says there was no fighting when rebels entered Sibut on Saturday.
The city is about 150km (95 miles) from Bangui.
Government troops and Chadian soldiers deployed as a buffer force had left their position hours before and a rebel spokesman said they took over the city because it was abandoned.
The government is reported to have fallen back to Damara, the last major town on the road to the capital.
Seleka - an alliance of three separate groups - accuses Mr Bozize of failing to honour a 2007 peace deal under which fighters who laid down their arms were meant to be paid.
They began their campaign a month ago and have taken several key towns and cities including Bambari and the diamond centre of Bria in their push towards the capital.
On Saturday, government officials confirmed that their forces' attempt to retake Bambari on Friday had been beaten back.
In Bangui, residents have reported sharp rises in staple food prices as the rebels draw closer.