A row has broken out over claims that UK spies had to be withdrawn after Russia and China managed to decode information in files leaked by Edward Snowden.
The newspaper reported that a Downing Street source said: "It is the case that Russians and Chinese have information. It has meant agents have had to be moved and that knowledge of how we operate has stopped us getting vital information."
The Sunday Times also quoted one senior Home Office official as saying that Snowden had “blood on his hands” - despite also quoting a Downing Street source as saying that no one had been harmed.
Glenn Greenwald criticised the Sunday Times report
Snowden, who fled the US after leaking tens of thousands of documents about surveillance programmes run by the NSA and foreign counterparts, including Britain's GCHQ, had previously said that the crucial data could not be decoded by foreign powers.
But now in what was described by former GCHQ director Sir David Omand as a "huge strategic setback" for the West, it was reported that Moscow and Beijing had "cracked" information that exposed intelligence-gathering techniques and could identify individual spies.
But Greenwald criticised the Sunday Times’ report, tweeting:
He also retweeted a post which said: “Unsourced, unverifiable nonsense smears by a group that knows it's losing, the spying fascists.”
Speaking on the Andrew Marr show this morning, Liberty chief Shami Chakrabati said that the report seemed to be an attempt to portray Snowden, “not as a whistleblower that some of us think of him as, but as a terrible traitor.”
The revelation came with renewed focus on spy agencies' powers to collect communications data in bulk, after a review - commissioned in the wake of the Snowden revelations - said the framework was "undemocratic" and must be entirely rewritten.
Terror laws watchdog David Anderson called for security services and police to keep intrusive powers to combat terrorism and serious crime but urged the Government to draw up "comprehensive and comprehensible" new legislation - including switching authorisation from ministers to judges.
The newspaper quoted a senior Home Office source as saying: "(Russian president Vladimir) Putin didn't give him asylum for nothing. His documents were encrypted but they weren't completely secure and we have now seen our agents and assets being targeted."
A British intelligence source was quoted as saying: "We know Russia and China have access to Snowden's material and will be going through it for years to come, searching for clues to identify potential targets.
"Snowden has done incalculable damage. In some cases the agencies have been forced to intervene and lift their agents from operations to prevent them from being identified and killed."
Sir David said: "I am not at all surprised that people are being pulled back and operations where people are exposed are having to be shut down, at least for the moment."