The Human Rights Watch has accused police in the Democratic Republic of Congo of carrying out dozens of extrajudicial killings during an anti-gang offensive.

According to a report released on Tuesday, the "Operation Likofi" kicked off last November with the aim of quelling a rise in armed robbery and other crimes by criminal gangs in the capital Kinshasa.

Police killed at least 51 unarmed young men and teenage boys outside their homes, or in open markets, for intimidating local population, the rights group said, adding that five were aged from 14 to 17 years old.

Around three dozen more people vanished during the three-month crackdown on organized crime gangs, the report added.

The mother of a man killed by police recounted how an officer told onlookers, “Come look. We killed a 'kuluna' (gang member) who made you suffer.”

The HRW called for the suspension of General Celestin Kanyama, who is said to be the commander of the operation, pending a judicial investigation of crimes associated with the op.

The group added that police in the capital carried out many raids and at times targeted innocent victims by mistake.

Authorities in the African country tried to cover up the crimes by issuing gag orders to doctors, threatening journalists, and denying relatives access to bodies of their loved ones, said the report, which was based on witness testimony.

Congo has witnessed back-to-back wars between 1998 and 2002. Its volatile east is home to armed groups fighting for control of the region's rich mineral resources while the capital city suffers from criminal gang violence.