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

The investigation found that Zeuz Global, a UK-registered firm, had used the postcodes of the Waldorf Hilton hotel and the One Aldwych hotel in central London, despite being initially registered at a block of flats in north London. When contacted, both hotels denied any knowledge of the firm's activities. The UK government confirmed that the flat in question was linked to the company.

"It's shocking that UK-registered companies are involved in the recruitment of mercenaries for a militia suspected of war crimes," said a spokesperson for Human Rights Watch. "This highlights the need for greater scrutiny of companies operating in conflict zones and the importance of holding them accountable for their actions."

The Rapid Support Forces, led by Mohamed Hamdan Dagalo, have been accused of numerous human rights abuses, including the use of child soldiers and forced displacement of civilians. The militia has also been linked to the Sudanese government's crackdown on opposition groups.

The recruitment of Colombian mercenaries by Zeuz Global and other UK-registered firms raises questions about the role of private military companies in conflict zones. "The use of mercenaries can exacerbate the situation and create more instability," said a spokesperson for the International Committee of the Red Cross. "It's essential that governments and companies take responsibility for their actions and ensure that they are not contributing to human suffering."

The investigation also highlights the challenges of regulating private military companies, which often operate in gray areas. "The lack of transparency and accountability in the private military industry is a major concern," said a spokesperson for the UK-based Campaign Against Arms Trade. "It's essential that governments take action to regulate this industry and prevent companies from operating with impunity."

The current status of Zeuz Global and the other UK-registered firms involved in the recruitment of Colombian mercenaries is unclear. The UK government has announced plans to review its regulations on private military companies, but it remains to be seen whether this will lead to any changes in the industry.

In the meantime, human rights groups and advocacy organizations are calling for greater scrutiny of companies operating in conflict zones and for governments to take action to prevent the use of mercenaries in human rights abuses.