The army of the Democratic Republic of Congo has accused Rwanda of dressing up prisoners in military uniforms in an effort to pass them off as newly-captured rebels linked to the Rwandan genocide.

It comes after Rwanda-backed M23 rebels in eastern DR Congo said they had captured fighters from the Democratic Forces for the Liberation of Rwanda (FDLR) - a militia founded by ethnic Hutus who took part in the 1994 genocide against Rwanda's Tutsis.

But the DR Congo military said a video allegedly showing the handover of 20 FDLR rebels at a border crossing was "faked".

M23 fighters have been advancing through eastern DR Congo since January, seizing Bukavu and Goma, the biggest city in the region.

The fighting has forced about 500,000 people from their homes, worsening an already dire humanitarian crisis, according to the UN.

In its statement, the Congolese military said the Rwandan video was a "faked incident in poor taste orchestrated with the sole aim of discrediting our army".

It said Rwanda had taken old FDLR prisoners and dressed them in new military uniforms to claim they had been newly captured in Goma.

"This is part of the Rwandan strategy to justify the invasion of parts of the DRC's territory," it added.

Rwanda has used the presence of FDLR forces in eastern Congo to justify its support for the M23.

The country previously denied backing the M23, but it has also stressed that due to the FDLR presence in eastern Congo it has a right to take military action in eastern Congo.

UN experts have previously estimated that between 3,000 and 4,000 Rwandan troops are in eastern Congo.

UN experts also reported last year that the Congolese military had been using several armed groups, including the FDLR, as proxies in the fight against the M23.

The genocide in Rwanda took place over 100 days in 1994.

The ethnic Hutu militia involved in killing up to 800,000 people - the vast majority from the Tutsi community - fled to what is now DR Congo, some forming the FDLR.

Kagame, who headed the rebel Tutsi force that ended the killing more than three decades ago, sees this "genocidal militia" as an existential threat.

On Thursday, gunfire and explosions ripped through a rally held by rebel leaders in Bukavu, the second-biggest city in the east. Videos showed chaotic scenes with bodies on the streets after the crowd fled.

M23 rebels seized Bukavu from government forces last month following their rapid advance through the region.

The rally had earlier been addressed by Corneille Nangaa, the head of an alliance of rebel groups that includes the M23.

The rebels accused DR Congo President Felix Tshisekedi's government of orchestrating the attack. However, Tshisekedi blamed it on "a foreign army" that he said was operating in the east.

The African Union and the UN have called for a ceasefire and for the rebels to withdraw from areas they now control.