Uganda, meanwhile, which also has troops in eastern Congo to take on Ugandan rebels based there, on Friday said it would "adopt a forward defensive posture" due to the fighting between

There has been fierce fighting as Rwanda-backed M23 rebels advance towards the second-largest city in eastern Democratic Republic of Congo, marking a further escalation in the region's conflict. M23 fighters have been moving south, towards Bukavu, the capital of South Kivu, after capturing the largest city in the region, Goma.

The United Nations expressed deep concern at reports of M23 rebels and Rwandan troops advancing south towards the Congolese city of Bukavu on Thursday, as the militants sought also to assert their control over east Congo's largest city Goma.

Congolese President Félix Tshisekedi has vowed to restore government authority in the east, where Rwanda-backed M23 rebels have seized control of the city of Goma and are reportedly advancing south to take more territory.

The Rwanda-backed armed group M23 vowed on Thursday to march on the DR Congo capital, Kinshasa, as its fighters made further advances in the mineral-rich east of the country.

SADC leaders pledged commitment at crisis talks in Zimbabwe as M23 rebels advance on Bukavu, just days after seizing Goma. The UN says at least 700 people have been killed since Sunday.