Fresh fighting has broken out between government and rebel forces in Chad's capital N'Djamena, reports say. Heavy weapons fire was heard near the palace where President Idriss Deby is said to be holding out. Rebels seized large parts of the city on Saturday, but military action subsided overnight as both sides claimed to be in control. Nearly 400 French and other foreign citizens were evacuated overnight to the Gabonese capital Libreville. The arriving evacuees appeared "harassed but happy", an AFP journalist in Libreville said. Several hundred others are gathered in designated areas in N'Djamena guarded by French troops. Ceasefire Witnesses heard anti-tank and automatic weapons fire coming from the city centre, starting at about 0500 local time (0400 GMT). AFP reported that government helicopters had attacked a column of rebels in the south of the city heading towards the main radio station. French Mirage combat planes have also been overflying the area. French officials say Paris is neutral in the military conflict but politically backs Mr Deby's government. France has also offered to evacuate Mr Deby but he refused to go, French officials told AFP. Meanwhile French Defence Minister Herve Morin confirmed that the Chadian army chief of staff, Daoud Soumain, had been killed in combat during the rebel advance on the capital. The fighting comes despite reports of a ceasefire brokered by Libyan leader Muammar Gaddafi. Rebel spokesman Abderamane Khoulamanla confirmed reports that Colonel Gaddafi had called rebel leader Mahamat Nouri to propose a ceasefire. "Our leader replied that he would agree to that if his two other partners in the rebellion would agree as well," Mr Khoulamanla said.