Manhattan skyline seen from One World Observatory at One World Trade Center | Spencer Platt/Getty Images British spies ‘complicit in US torture’ post 9/11 Report by UK parliament’s intelligence and security committee is critical of of MI5 and MI6.

British intelligence agencies turned a blind eye to torture and mistreatment of detainees post 9/11, according to two reports by the U.K. parliament's intelligence and security committee.

The ISC reports, which were commissioned after a judge-led inquiry set up by David Cameron was scrapped by the government in January 2012, said it was "beyond doubt" the U.K. knew how the U.S. mistreated some detainees.

The U.K. also suggested, planned or agreed to 28 rendition operations, in which individuals are sent to other countries for imprisonment or interrogation probably using methods that are illegal in the country doing the rendering. In three cases U.K. intelligence agencies paid or offered to pay others to conduct a rendition operation. The report said there was no understanding in government of rendition or the need for a clear policy in this area.

The report also found 13 incidents where U.K. personnel witnessed mistreatment, 128 times where officers were told by foreign liaison services about mistreatment, and 25 instances in which personnel were told by detainees that they had been mistreated. In some instances these cases were correctly investigated but the report said this was not consistent. The ISC found no evidence that British officials physically mistreated detainees themselves.

However, the report stated that the committee did not find a "smoking gun" to indicate agencies had a policy of overlooking reports of mistreatment or rendition.

In a written statement, Prime Minister Theresa May said: "With the benefit of hindsight, it is clear that U.K. personnel were working within a new and challenging operating environment for which, in some cases, they were not prepared."

"It took too long to recognize that guidance and training for staff was inadequate, and too long to understand fully and take appropriate action on the risks arising from our engagement with international partners on detainee issues," the statement said.