Top UN investigator calls for CIA prosecution over torture programs

The UN's top special investigator for counterterrorism is calling for the prosecution of senior US officials who authorised and carried out torture as part of former President George W Bush's national security policies.

Ben Emmerson, the UN's special rapporteur on counterterrorism and human rights, says all CIA and other US government officials who carried out waterboarding and other torture must also be prosecuted.

In a statement on Wednesday released in Geneva, Emmerson said the US Senate Intelligence Committee's report shows "there was a clear policy orchestrated at a high level within the Bush administration, which allowed (it) to commit systematic crimes and gross violations of international human rights law".

He says those responsible for the "criminal conspiracy ... must face criminal penalties commensurate with the gravity of their crimes".