British intelligence agencies spoke to US counterparts about a report into CIA interrogation before it was published, Downing Street has said.
Committee chair Dianne Feinstein said CIA interrogation techniques amounted to torture
A spokeswoman did not say the UK had asked for information to be left out - but said if requests were made it was not to hide UK involvement in torture.
No 10 had previously said it had not requested redactions, but it now says any requests would have been made for "national security reasons".
The report found "brutal" tactics used.
The published report, which looked at treatment of detainees in the years after the 9/11 attacks in 2001, is a 525-page summary of a 6,000-page document produced by Democrats on the Senate Intelligence Committee. The full document remains classified.
Dianne Feinstein, chair of the Senate committee, said CIA tactics - which included repeated waterboarding, slapping, stress positions and sleep deprivation - amounted to torture.
Ground 'shifting'
The published report contains no reference to UK agencies.
BBC political correspondent Iain Watson said that on Wednesday "Downing Street said to the best of their knowledge they hadn't asked for any redactions from that report".
But he said the "ground seemed to be shifting" on Thursday, as a Downing Street spokeswoman said there had been a conversation between UK and US intelligence services about the executive summary of the report.
"So it looks as though redactions were requested," our correspondent said.
"But she [the spokeswoman] went on to say these were on the grounds of national security, not on the grounds of British complicity in torture or any British involvement, either directly or indirectly, in the mistreatment of suspects."
Government ministers and UK security and intelligence agencies MI5 and MI6 have always said torture would never be used by Britain to extract information.
Parliament's intelligence and security committee is currently examining the question of whether the UK was complicit in the US mistreatment of suspects.
On Thursday, Deputy Prime Minister Nick Clegg said he would be open to a full judicial inquiry if the committee failed to answer key questions.
BBC
