Attorney general Dominic Grieve will rule on whether the prosecution of the Guardian under the Official Secrets Act was in the public interest before a case could proceed, the paper reports today.
A spokesman told the Guardian that Grieve would liaise with the Crown Prosecution Service to assess whether there is sufficient evidence that the act had been breached and whether such a step would be in the public interest.
"It is a matter for the police to decide how best to carry out any investigation," he said. "If the police provide evidence that would support a charge under section 5 of the Official Secrets Act the attorney general's consent would be required.
"If that stage is reached, the attorney general, with the DPP, will consider whether there is sufficient evidence and whether the public interest is in favour of bringing a prosecution."
Scotland Yard's decision to use the act as part of its bid to force Guardian journalists including Nick Davies and Amelia Hill, who revealed that Milly Dowler had her phone targeted by the News of the World, to reveal their sources has been condemned by other newspapers.
Alan Rusbridger, the Guardian's editor-in-chief, has said the paper will resist the attempt by the Metropolitan police to reveal its sources "to the utmost".
Scotland Yard applied for a production order last week against the Guardian "in order to seek evidence of offences connected to potential breaches relating to misconduct in public office and the Official Secrets Act".
- According to the Guardian, Milly Dowler's family have been offered a £2m-plus settlement by News International.