The UN recently boosted its peacekeeping force with a special combat force aimed at disarming rebel groups. Photo: BBC

He spoke to President Paul Kagame after Rwanda accused DR Congo of deliberately bombing its territory, killing a woman and wounding her baby.

Mr Ban's assistant, Edmond Mulet, reportedly told UN members M23 rebels had been seen firing into Rwanda.

DR Congo and the UN accuse Rwanda of backing the M23, a charge it denies.

Their troops have been pounding rebel positions on the Congolese side of the border with Rwanda since last week.

Congolese government spokesman Lambert Mende told the BBC's Newsday programme that M23 rebels were firing onto Rwandan territory "in order to give Rwanda a pretext for coming in openly in this war".

The UN peacekeeping mission in DR Congo, Monusco, recently deployed a new 3,000-strong intervention brigade to

tackle the rebels.

'Cannot be tolerated'

Rwanda's Foreign Minister Louise Mushikiwabo said 13 "bombs and rockets" were fired into Rwanda on Wednesday and 10 on Thursday.

This brought to 34 the number of attacks Congolese have carried out on Rwanda in the last month, she said.

She accused DR Congo forces of targeting Rwandan civilians and said: "We have remained restrained for as long as we can but this provocation can no longer be tolerated."

BBC Great Lakes service editor Ally Yusuf Mugenzi says that even when Rwanda twice invaded Congolese territory during the 1990s, it never made such strong accusations against the Congolese army.

Congolese army spokesman Col Olivier Hamuli told the BBC that his forces would never fire at civilian populations.

"That could only be rebels," he said, adding that M23 fighters, and not soldiers, were in the area from which the shells were fired.

This was backed up by Mr Mulet, who told the UN Security Council that UN forces in the DR Congo had witnessed M23 rebels firing artillery into Rwanda but not the Congolese army, diplomats said.

Mr Mulet ended the session by informing members that Mr Ban had telephoned Mr Kagame to urge restraint.

At least 800,000 people have fled their homes in DR Congo since the M23 launched its rebellion in April 2012.

The M23 is made up of deserters from the Congolese army and are mostly ethnic Tutsis, like Rwanda's leadership.

Eastern DR Congo has been wracked by conflict since 1994, when Hutu militias fled across the border from Rwanda after carrying out a genocide against Tutsis and moderate Hutus.