Some 200,000 people have been killed in three years of fighting between the Sudanese army and the paramilitary Rapid Support Forces (RSF) -- a conflict that has unleashed one of the world's worst humanitarian crises.

The HRW report, published late Monday, details how former Colombian soldiers -- hired by private companies linked to figures close to the Emirati government -- have ended up fighting alongside the RSF in Sudan.

"The recruitment of Colombian private military contractors adds to a growing body of evidence that the UAE provides military support to the Rapid Support Forces, which have repeatedly carried out heinous atrocities in Sudan," said Mausi Segun, executive director of HRW's Africa Division.

Colombian ex-soldiers, who have extensive battle experience from their own country's six-decade-long armed conflict, are frequently recruited by belligerents in other wars.

According to the HRW report, they were present during some of the worst episodes in Sudan, such as the brutal takeover of the Darfur city of El-Fasher in 2025.

There is also evidence of their involvement in the use of mortars, heavy weapons and drones, as well as the training of child soldiers.

An AFP investigation in December revealed details of the recruitment scheme, including the involvement of Emirati firm Global Security Services Group (GSSG) along with a myriad of companies in Colombia and Panama.

GSSG was founded by Ahmed Mohamed al-Humairi, secretary general of the Emirati presidential court.

The company has held government contracts and is currently registered in the name of an associate of Al-Humairi, according to HRW.

The UAE denies allegations of recruiting mercenaries.

A government official told AFP that the country "does not permit its territory to be used for the recruitment, training, financing or transit of foreign fighters to any conflict, including Sudan."

Last year, Colombia passed a law in Congress prohibiting mercenary activities, but the recruitment of fighters continues.

The United Nations estimates that 10,000 Colombians have been recruited to participate in conflicts around the world.