The Sunday Times and the BBC cited senior government and intelligence officials as saying that MI6 agents, the British intelligence agency which supplies the British government with foreign intelligence, had been pulled out of live operations in hostile countries, without naming them.
The report said the move came after Russia and China were able to decrypt more than one million files held by Snowden, the former American security contractor, after mounting one of the largest leaks in US history.
Senior government sources confirmed that China had also cracked the encrypted documents, which contain details of secret intelligence techniques and information that could allow British and American spies to be identified.
Snowden, 31, a former contractor at the Central Intelligence Agency and National Security Agency, downloaded 1.7 million secret documents from western intelligence agencies in 2013 and released details of sensitive surveillance programmes to the media.
Two weeks after his initial leak in June 2013, Snowden fled Hong Kong for Moscow where he claimed political asylum. Snowden, who is wanted in the US, has remained in Russia since fleeing Hong Kong, a special administrative region of China.
British Prime Minister David Cameron’s aides confirmed on Saturday night the material was now in the hands of spy chiefs in Moscow and Beijing.
A senior 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. There is no evidence of anyone being harmed.”
The confirmation is the first evidence that Snowden’s disclosures have exacted a human toll, The Times said.
“Why do you think Snowden ended up in Russia?” said a senior Home Office source. “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 said: “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,” The Times quoted the source as saying. One senior Home Office official accused Snowden of having “blood on his hands”, although Downing Street said there was “no evidence of anyone being harmed”.
Sir David Omand, the former director of UK’s government Communications Headquarters, said the news that Russia and China had access to Snowden’s material was a “huge strategic setback” that was “harming” to Britain, America and their NATO allies.
Omand said the leaked information would enable China and Russia to plug any of their intelligence capability gaps and warned that could spark “a global intelligence arms race”.
A US intelligence source told the paper said the damage done by Snowden was “far greater than what has been admitted”.
It is not clear whether Russia and China stole Snowden’s data, or whether he voluntarily handed over his secret documents in order to remain at liberty in Hong Kong and Moscow, the report said.
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