The United Nations says the deployment of a spy drone by UN peacekeepers in the east of the Democratic Republic of Congo has been delayed by several months

The UN has obtained an unarmed surveillance drone from Italian company Selex ES that was scheduled to be deployed in Congo near its border with Rwanda in August.

"There has been some delay much to my chagrin but these have to do with the rules that member states have made upon us as far as procurement is concerned," UN peacekeeping chief Herve Ladsous said during a news conference on Thursday at the UN headquarters in New York.

"Now the goal is definitely for the first days of December," Ladsous added.

Congolese troops and UN peacekeepers have been fighting for over a year to crush a rebellion by March 23 movement (M23) fighters who defected from the Congolese army in April 2012 in protest over alleged mistreatment in the army.

UN experts have accused neighboring Rwanda of sending fighters and arms to Congo to support M23 rebels.

Rwanda has always denied the charges that it is backing the M23, but Kigali has never publicly condemned the militia, which is strengthening its grip over the provinces of North Kivu and South Kivu in the eastern Congo.

Last month, fighting between M23 insurgents and the Congolese army, backed by UN peacekeepers, broke out again.

"It was a bit worrying two weeks ago but I think we are making progress," the UN peacekeeping chief said on Thursday.

"The M23 group has been pushed back towards to the north to such a place that it does not anymore pose the direct threat that it had posed for such a long time either on the city of Goma or on the surrounding IDP (internally displace people) camps or indeed on the positions of MONUSCO," Ladsous said.

The M23 rebels seized Goma, the main city in the eastern Democratic Republic of Congo, on November 20, 2012 after UN peacekeepers gave up the battle for the frontier city. The rebels withdrew from the city on December 1, 2012 under a ceasefire accord.

During a November 24 summit of the International Conference on the Great Lakes Region (ICGLR), an 11-member regional bloc, the Congolese government pledged to start peace talks with M23 rebels.

The talks between Kinshasa and the M23 began in December 2012 but broke down in April 2013.

Since early May 2012, nearly three million people have fled their homes in eastern Congo. About 2.5 million have resettled in Congo, but about 500,000 have crossed into neighboring Rwanda and Uganda.