The UN rights chief on Thursday said DR Congo had used "excessive force" during deadly clashes with demonstrators in the capital and called on Kinshasa to reach out to the opposition to avert a "large-scale crisis"

"The authorities need to pull back from their extremely confrontational position and build bridges with the opposition," Zeid Ra'ad Al Hussein said in a statement issued in Geneva in the wake of confrontations between security forces and opposition protestors in Kinshasa on Monday and Tuesday.

Zeid said the violence, marked by many civilian deaths, large-scale looting, and destructive attacks on government and opposition premises, "provide a stark warning that a large-scale crisis could be just around the corner."

"The writing is on the wall," he said.

On Wednesday, DR Congo police said 32 people had been killed during the violence, while the opposition reported "more than 100 dead", some of them burned alive.

Zeid's office put the toll at at least 50, with four police officers among the dead.

Opposition groups had organised demonstrations on Monday to demand the resignation of President Joseph Kabila, who has ruled since 2001 and, under the constitution, is barred from running for another term.

Although Kabila's current term ends on December 20, no date for new elections has been announced and there are fears Kabila plans to stay in power.

"Some civilians were killed by gunshots to the head or chest, and I strongly condemn the clearly excessive use of force by defence and security forces against demonstrators in the capital," Zeid said.

The human rights chief called on the government to withdraw personnel of the Republican Guard -- a military unit under the direct control of the head of state -- from the streets of the capital and to instead deploy "properly trained police forces with appropriate equipment for crowd control."

On Wednesday, police spokesman Pierre-Rombaut Mwana-Mputu defended the security deployment in Kinshasa during the unrest.

"The national police was backed by members of the (army) to stop the acts of looting and vandalism," he told reporters.

More than a 100 soldiers were posted on Thursday at the Limete junction where Monday's protest march began.

Also Thursday, Kinshasa lashed out at French President Francois Hollande over his criticism of the DRC government's handling of the protests.

Spokesman Lambert Mende said he wondered "whether DRC had become a new overseas territory resulting from new (French) conquests."

He accused Hollande of scolding Kinshasa "in the tone of a schoolmaster" and of being selective in his compassion towards the victims of the unrest.

At a news conference at the United Nations in New York on Tuesday, Hollande called the violence "unacceptable and intolerable" and denounced the burning of opposition premises.

"The constitution must be respected and elections must take place," he said.

Kabila's political foes have formed a "Gathering" around the opposition Union for Democracy and Social Progress (UDPS) party founded by veteran Etienne Tshisekedi, 83, who has called himself the country's "president elect" since the last presidential poll in November 2011, which was marred by massive fraud.

Leaders of the Gathering were set to meet Thursday afternoon to "decide on a day of national mourning during the burial of our fighters killed by the regime", UDPS spokesman Bruno Tshibala told AFP.

"We plan to go in a cortege to the cemetery, with president Tshisekedi at our head," he added.

Tshibala accused Health Minister Felix Kabange Numbi of doing the rounds "of the morgues to take away the bodies of our fighters", after Kinshasa's governor Andre Kimbuta said that city authorities would take charge of funerals.

Numbi was unavailable for comment on the allegation.

Kabila's office has accused the opposition of having transformed Monday's march into "bloody riots", while Tshibala described the violence as a "fire" planned by a "bloodthirsty government".

The head of state, who was first placed in power at the height of the Second Congolese War after his father Laurent-Desire Kabila was murdered by a palace adjutant, is under pressure from the international community to ensure fair elections are held quickly.

The UN Security Council called on Wednesday for the restoration of calm and for "credible elections" in the vast, mineral-rich country.