The Guardian and the Independent newspapers are embroiled in a row over the latter's exclusive story which claims the UK runs a secret internet monitoring station in the Middle East to intercept data on behalf of Britain's GCHQ and America's National Security Agency (NSA).
The Independent article cited leaked documents obtained from the NSA by Edward Snowden, the surveillance whistleblower who has been granted a one-year asylum in Russia.
The story also claimed that the Guardian had made a deal with the government to not publish any material in the Snowden documents that could potentially endanger national security.
Snowden denied providing material to the Independent, or even speaking to reporters there, in a statement on the Guardian blog run by American journalist Green Greenwald, who broke the surveillance scoop.
Snowden, a former NSA IT contractor, also accused Whitehall of being the source of sensitive material leaked to the Independent in Greenwald's Comment is Free blog.
"It appears that the UK government is now seeking to create an appearance that the Guardian and Washington Post's disclosures are harmful, and they are doing so by intentionally leaking harmful information to the Independent and attributing it to others," he said.
The development came after the scandal over the UK's use of the Terrorism Act to detain Greenwald's partner David Miranda at Heathrow airport.
Miranda, who was detained for nine hours, is taking legal action against the British government over the police seizing his property, including electronic equipment.
Greenwald, who is based in Rio de Janeiro, also rejected the Independent's claims of any kind of non-disclosure deal between the Guardian and the government.
But the Independent's Oliver Wright, one of the authors of the exclusive, tweeted: "For the record: The Independent was not leaked or duped into publishing today's front page story by the government."