The evidence suggests, investigators said, British agencies had a hard balancing act - as a junior partner with limited influence, careful not to upset USA counterparts for fear of losing intelligence supplied by the detainees that could have been vital in preventing an attack in Britain.
Although the committee did not find any evidence that British intelligence officers directly mistreated or tortured militant suspects, they reveal new evidence about the scale of cases where British agents were aware of mistreatment.
"In our view the United Kingdom tolerated actions, and took others, that we regard as inexcusable", the Intelligence and Security Committee said.
A further 198 cases showed that British spy agencies received intelligence from liaison services "which had been obtained from detainees who knew they had been mistreated - or with no indication as to how the detainee had been treated but where we consider they should have suspected mistreatment".
But the report said it had found 232 cases where British personnel continued to supply questions or intelligence to allies after they knew about suspected mistreatment.
The committee found British intelligence officers were involved in incidents of mistreatment ranging from officers either witnessing torture first hand to passing on intelligence knowing it could be used in illegal interrogations.
Murió el actor y guionista Juan Carlos Mastrangelo
Según se informó, el artista cayó del balcón de su departamento, en un quinto piso de un edificio del barrio porteño de Belgrano . La información la confirmó el actor e imitador Fernando Ramírez, amigo de Mastrangelo y con quien compartía la obra Copycat .
The report expressed "serious concerns" about the conduct and called some actions by British officials inexcusable.
"Our staff were under pressure to deliver intelligence on the threat", the official said.
The ISC stated that, while they found "no smoking gun" in relation to British agents deliberately overlooking cases of US-administered torture, more could have been done at both agency and ministerial level to influence U.S. behaviors concerning how they dealt with suspects.
The Intelligence and Security Committee found no "smoking gun" indicating that security and intelligence agencies had a policy of deliberately overlooking reports of mistreatment and no evidence that United Kingdom officers directly carried out physical mistreatment of detainees.
Prime Minister Theresa May said in a written response to the report that intelligence officers had been working in a challenging environment they were not prepared for.