There has been heavy fighting between the army of the Democratic Republic of Congo and M23 rebels some 20km (12.4 miles) from the eastern city of Goma.
A BBC correspondent says M23 wants to seize the regional capital to force the government to make concessions.
The rebels already hold a substantial swathe of territory bordering Uganda and Rwanda.
Kenya’s former President Uhuru Kenyatta has been in Goma to assess the security situation.
Earlier he held talks with DR Congo’s President Felix Tshisekedi in a bid to end the conflict and resolve tensions with Rwanda which is accused of supporting the rebels. It denies the allegation.
