A cross-party group of MPs have tabled a motion calling for strict guidance to be issued to police forces reminding them of the need to protect press freedom.
In the Commons motion, they claim “many police forces fail to recognise the importance of a journalist’s right to protect his or her sources”.
The move follows a failed legal bid to force journalist Suzanne Breen to hand over information about the Real IRA.
The motion was tabled by Labour’s John McDonnell (Hayes and Harlington), secretary of the National Union of Journalists’ parliamentary group.
It has support from all main parties, including Liberal Democrat culture, media and sport spokesman Don Foster and Tory former minister Peter Bottomley.
The motion states “that the protection of confidential sources is internationally recognised as one of the basic principles of press freedom”.
It said any attempts to force journalists to disclose information to the security services “undermine the confidence and candour with which sources will talk to journalists”, damaging the ability of the press to hold the authorities to account.
The motion “calls on the Government to issue guidance to police forces across the UK to remind them of the need to respect press freedom”.
After her legal victory last week, Breen, the northern editor of the Dublin-published Sunday Tribune, said the ruling set a precedent that would protect the profession of investigative journalism.
A judge in Belfast ruled that compelling the reporter to hand over notes and phone records about the dissident republican group’s involvement in the murder of two British soldiers would put her life in danger.
Police Service of Northern Ireland chief constable Sir Hugh Orde took the court action under UK anti-terror legislation in a bid to catch the gunmen who killed Patrick Azimkar, 21, from London, and Mark Quinsey, 23, from Birmingham, at the gates of Massereene Army Base in Antrim in March.