The Democratic Republic of Congo on Monday flatly rejected international calls to investigate a video purporting to show a massacre of unarmed men and women by DR Congo soldiers.

The government's refusal came as two other videos showing alleged abuses by DR Congo soldiers began circulating on social media networks.

The seven-minute video that emerged over the weekend shows a group of uniformed men opening fire, then walking among at least 20 bodies, apparently in the violence-wracked central Kasai region.

Washington and Paris both called on the government to open an inquiry, with a US State Department spokesman condemning the "heinous abuses" seen in the video.

UN High Commissioner for Human Rights Zeid Ra'ad Al Hussein also called on Congo to investigate and to implement a "comprehensive peace plan" to halt escalating violence in the country.

But Kinshasha, saying it was routinely the target of "malicious rumours", brushed off the demands.

In a statement calling the video the work of "anonymous amateurs", the government said "it is not our job to prove the innocence of the FARDC", the name of DR Congo's armed forces.

"It's up to the accusers, unknown for now, to prove these facts so that all implicated parties can respond, in line with the law."

On Saturday, the government had nonetheless acknowledged possible "excesses and abuse" by soldiers, two of whom it said were on trial for unspecified charges.

But a government spokesman, Lambert Mende, said Monday that they were not being charged with war crimes or crimes against humanity, but "violations of orders" and "extortion" during an operation in Mwanza Lomba, the Kasai village where the video was filmed.

- New videos emerge -

The Kasai region has been plagued by violence since mid-August when government forces killed a tribal chief and militia leader, Kamwina Nsapu, who had rebelled against the central government.

At least 200 people have been killed since then, leading the UN mission in the country to pledge at least 100 peacekeepers for the region.

The authenticity of the Kasai video has not been proven, but the two videos that emerged Monday, supposedly taken in the same region, also purportedly show abuses by DR Congo forces.

In one, a woman wearing a red band, often used by the Nsapu rebels, is lying on the ground, apparently shot in the hip.

She is being questioned by unseen men speaking in Tshiluba, a language of Kasai-Central.

The woman is then kicked in the head and the neck, and jeered at when she asks to be evacuated.

Another video shows at least eight children wounded or killed by bullets, surrounded by men in uniforms or navy blue outfits similar to those worn by DR Congo police officers.

Shots can be heard offscreen, and insults are hurled at the victims in both Tshiluba and Lingala, the language used by Congo's army.

A spokesman for the UN force, MONUSCO, condemned atrocities by Nsapu's militia in early February as well as the use of disproportionate force by the national army.

As well as the tribal conflict in Kasai, Congo has been rocked by political violence after President Joseph Kabila failed to step down at the end of his second and final term in December.

Under a power-sharing deal signed on New Year's Eve, Kabila will remain in office until the "end of 2017" but a transition council was also to be established.

An opposition coalition, Rassemblement, condemned the government's attitude of "permanent denial" in the face of alleged abuses, and called for an independent international inquiry into acts of "revolting cruelty".

But a spokesman for Kabila's Alliance for a Presidential Majority, Andre-Alain Atundu, said that he would not respond to "rumours", and that the government would wait to receive information before "determining what is true or false".

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