An AU spokesman said on Sunday that 7,000 troops were not enough to deal with implementation of the Darfur peace agreement that was signed by the Sudanese government and one rebel faction in May.
Noureddine Mezni said: "It will be a matter of battalions. I cannot specify how many battalions we are going to bring, but we are going to increase the number of troops".
A battalion is usually composed of 600 to 800 soldiers.
Mezni said more troops were also needed to bolster the operation in the arid region the size of France.
"We have additional tasks. It is important to increase the number. We are working on that," he said, adding if approved troops could begin deploying within a matter of weeks.
The soldiers would come from countries already contributing troops in Darfur - Nigeria, Rwanda, South Africa and Senegal.
The AU's mandate in Darfur had been set to expire on September 30 and the pan-African body had said it could not continue beyond October because it was out of money and needed more equipment such as helicopters.
The UN had hoped to send 20,000 soldiers and police into Darfur to replace the AU forces, which have been unable to stem the fighting that has killed an estimated 200,000 people and forced 2.5 million from their homes since 2003.
But the Sudanese government has refused to allow UN forces into Darfur, calling it a Western ploy to recolonise Sudan.
With aid experts predicting a new humanitarian catastrophe in Darfur if African troops withdrew, the AU agreed last week to extend its mission until December 31, with logistical and material support from the UN and funding from Arab states.
In New York, efforts were to continue on Monday at the UN to gear up for a possible mission transfer.