GOMA, Congo -- A leader of the M23 rebels who were forced to retreat from most of their strongholds in eastern Congo is now calling for a ceasefire.

In a statement released Sunday, M23 president Bertrand Bisimwa called on his fighters to put down their weapons, and urged the Congolese military to cease all hostilities so as to allow peace talks to go forward.

After an 18-month rebellion that saw the rebels briefly overtake the city of Goma last year, the Congolese military stepped up its offensive in October. It quickly retook a series of towns, and M23 fighters headed for the hills.

Bisimwa is now in Uganda, where negotiations between the two sides have been under way, though they have repeatedly stalled in the past