Political pressure on the Guardian newspaper over its handling of leaked secret intelligence material intensified as a senior Tory wrote to the Director of Public Prosecutions.

Former defence secretary Liam Fox sought the advice of Alison Saunders over the potential for legal action over the transfer overseas of files leaked by US whistleblower Edward Snowden.

Cabinet ministers said revelations of the surveillance activities by US and UK intelligence agencies hurt national security but any legal action was an issue for the Attorney General.

Guardian editor Alan Rusbridger is to be questioned by MPs in December about the publication of files about the operations of eavesdropping agency GCHQ and the US National Security Agency.

He faces demands from other Tory MPs to confirm if anyone at the Guardian "directed, permitted, facilitated or acquiesced" in the transfer of the Snowden files to the US or elsewhere.

Dr Foxsaid there were "accusations that the Guardian passed the names of GCHQ agents to foreign journalists and bloggers".

"Would such activities, if true, constitute an offence under the Terrorism Act 2000 or related legislation, particularly the passing of details of identified security personnel?" he asked.

Asked about the possibility of a prosecution, Foreign Secretary William Hague said: "That is something on which the Attorney General would decide and does decide. So you can see the Government's position on that as that isn't something that hasn't happened."

Defence Secretary Phillip Hammond said the "cat was out of the bag" and legal action could not "reverse the damage" already caused. "As to whether any particular prosecution or action would make much difference, I think that's a very different issue and it's one for the Attorney General," he said.