The largest rebel group destabilising parts of the Democratic Republic of Congo has itself been “seriously destabilised” by outside attacks and internal splits, a UN panel reported on Thursday.

The FDLR was greatly weakened by military operations carried out last year and early this year by the DRC army and Congolese Mai Mai militias, a team of UN experts told the Security Council.

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The Security Council reviewed the experts’ report on the same day as it renewed an arms embargo and financial sanctions aimed at the rebel groups said to have carried out atrocities in eastern DRC.

A Council resolution adopted unanimously on Thursday also calls on the DRC government to carry out elections in November.

Any delay would likely allow President Joseph Kabila to remain in office past the DRC constitution’s requirement that he step down at the completion of his second term five months from now.

The move by Mr Kabila could trigger violence of a magnitude greater than was experienced earlier this year when security forces killed about 40 civilians who were demanding that the president leave office.

The killings were cited by the Obama administration as a factor behind its decision on Thursday to impose financial sanctions on Céléstin Kanyama, chief of police in Kinshasa.

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DRC government representatives criticised both the UN’s call for timely elections and the US move to punish Mr Kanyama.

The DRC’s UN Ambassador Ignace Gata Mavita wa Lufuta said the Security Council resolution should not have referred to the electoral process and that the government’s preparations for the voting “should not interpreted as a pretext to defer the elections.”

An advisor to President Kabila condemned the US action, calling it an infringement on DRC sovereignty and a blow to bilateral relations. “It will also embolden those who seek to divide our nation and impede our democratic processes,” said Barnabé Kikaya Bin Karubi.

The UN experts group warned that the FDLR has not yet been defeated and could regroup.