Roger Meece vowed to protect population centers from advancing rebels as reports indicated the Congolese army reclaimed two towns recently captured by the insurgents, the BBC reported Wednesday.
"We have since the beginning and we're continuing to make adjustments in deployment, including bringing personnel that are available from elsewhere," said Meece, the U.N. special representative to the Democratic Republic of Congo.
Members of the M23 movement -- named after a failed peace agreement signed March 23, 2009 -- said they don't intend to try to capture Goma and want to negotiate with the government, the report said.
The Congolese government and the United Nations have said Rwanda is backing the rebels, a claim Kigali has denied.
The rebels support Gen. Bosco Ntaganda, who is wanted for war crimes by the International Criminal Court in The Hague, Netherlands. Ntaganda is a former member of the Rwandan Patriotic Army and allegedly a former deputy chief of the general staff of the Patriotic Forces for the Liberation of Congo.