UK-registered firms have been implicated in the recruitment of Colombian mercenaries in Sudan, according to a recent investigation by The Guardian. The companies, set up by individuals sanctioned by the US, hired the fighters for the Rapid Support Forces, a paramilitary group widely suspected of committing war crimes in Sudan.

The investigation found that the firms, including Zeuz Global, had used various addresses in central London, including a block of flats in north London and the postcodes of the Waldorf Hilton hotel and the One Aldwych hotel. When contacted, both hotels denied any knowledge of the firms' activities. Zeuz Global was once registered at a block of flats in north London, but has since used the postcodes of the Waldorf Hilton hotel and the nearby One Aldwych hotel.

"We are shocked and disturbed by these findings," said a spokesperson for the Waldorf Hilton hotel. "We have no knowledge of any company using our postcode for illicit activities." A spokesperson for the One Aldwych hotel also denied any involvement, stating, "We are not aware of any company using our postcode for such purposes."

The Rapid Support Forces, led by Mohamed Hamdan Dagalo, have been accused of committing human rights abuses and war crimes in Sudan, including the displacement of civilians and the use of child soldiers. The US has imposed sanctions on several individuals and entities linked to the group, including Dagalo.

The recruitment of Colombian mercenaries by UK-registered firms highlights the complex and often opaque nature of the private military industry. The industry has grown significantly in recent years, with companies operating in conflict zones around the world.

"This is a classic example of how the private military industry can be used to facilitate human rights abuses and war crimes," said a spokesperson for Human Rights Watch. "We urge the UK government to take immediate action to investigate these allegations and to hold those responsible accountable."

The investigation by The Guardian raises questions about the UK's role in the recruitment of mercenaries and the oversight of private military companies operating in conflict zones. The UK government has been criticized for its lack of transparency and regulation of the private military industry.

The current status of the investigation and the next developments are unclear. However, the findings of The Guardian's investigation are likely to spark a renewed debate about the role of private military companies in conflict zones and the need for greater transparency and regulation.

In a statement, the UK Foreign and Commonwealth Office said it was "aware of the allegations" and was "looking into the matter." The US State Department also declined to comment, citing an ongoing investigation.

The recruitment of Colombian mercenaries by UK-registered firms is a complex issue that highlights the need for greater transparency and regulation of the private military industry. As the investigation continues, it is likely that more information will come to light, and the UK government will face increased pressure to take action to address the allegations.