The United Nations and Democratic Republic of Congo army used helicopter gunships on Thursday to attack army mutineers thought to be threatening the main eastern city of Goma.

Three helicopters from the UN country mission and two from the DRC army (FARDC) were seen around the villages of Nkokwe and Bukima, where the so-called M23 rebels are thought to have positions.

The UN and the Congolese army sent MI24 and MI25 helicopters flown by Ukrainian pilots. The gunships, first made by the Soviet Union, strafed hillsides with 30mm rounds and fired rockets, a UN source said.

"We made several passes on rebel positions," the UN official said.

The UN and the troops from the Democratic Republic of Congo, which claims the rebels are a Rwandan proxy, had earlier deployed tanks around Goma in Nord-Kivu province.

However, the rebels said they had no plans to seize the regional capital and only wanted to negotiate with the government in Kinshasa.

"The FARDC are currently attacking our positions, but they don't know where we are. There's no problem," a colonel from the rebels said.

The M23 rebels — named after a failed 2009 peace deal signed on March 23 — are led by Bosco Ntaganda, nicknamed the "Terminator", who is wanted by the International Criminal Court for recruiting child soldiers a decade ago.

His co-accused and former boss Thomas Lubanga was sentenced to 14 years in jail on Tuesday.

The mutineers are ex-rebels who were integrated into the regular army in 2009 as part of a deal that followed their failed 2008 offensive on Goma, under the command of Tutsi leader Laurent Nkunda.

They defected in April, ostensibly over pay, but experts argue Ntaganda and his men are flexing military muscle to clinch further rights over the area's lucrative mines.

In Thursday's gunship attacks, a group of women working in fields near Bukima claimed they were caught in the crossfire.

"We were hiding in the banana groves when the helicopters opened fire. There was one person with us who was hit and died immediately," said one woman who asked not to be named.

Nkokwe and Bukima are on the western border of the Virunga national park, some 50km from Goma and home to critically endangered mountain gorillas and the location of two active volcanoes.

The M23 mutineers had launched an offensive in recent days, easily overwhelming the FARDC. Around 600 regular troops and tens of thousands of civilians were forced to seek refuge in Uganda.

"Our mission is not to go to Goma. We are strong but we are also disciplined," M23 spokesman Vianney Kazarama said.

The mutineers had seized a number of towns along the Ugandan border and promptly withdrew from all but Bunagana.

"We have pulled out of those towns, our mission is not to control them. What we want is that the Congolese government sit down at the negotiating table," Kazarama said.

Almost uninterrupted conflict over DR Congo's vast mineral resources — which include gold, diamonds, coltan, tin, tungsten and many others — has left at least two million people dead since 1999, say rights groups.

A diplomat in Kinshasa said an M23 offensive on Goma appeared unlikely.