Critics round on police for using Offical Secrets Act to try to force Guardian to reveal source of phone-hacking story

Leading journalists and lawyers on Saturday accused Scotland Yard of launching "a direct attack on a free press" after it invoked the Official Secrets Act in an attempt to force journalists to reveal their sources.

Lawyers acting for the Metropolitan Police will on Friday apply for an order under the 1989 act requiring the Guardian to hand over documents that could identify the source of information for several articles published as part of the newspaper's investigation into phone hacking.

The Society of Editors on Saturday joined the Index on Censorship in criticising the legal manoeuvre, while a leading QC suggested it could breach human rights laws.

"Scotland Yard's outrageous and unjustified attempt to force the Guardian to reveal its sources in its phone-hacking investigation is a direct attack on a free press," said John Kampfner, chief executive of Index on Censorship. "This is a shocking move to intimidate the media using the Official Secrets Act, one of the state's most draconian pieces of legislation."

Bob Satchwell, executive director of the Society of Editors, described the Met's behaviour as "outrageous, pointless and baffling". He said: "The Official Secrets Act is designed to protect national security, so there is no justification in this case. The law, and particularly the Human Rights Act, is supposed to protect journalists' sources."

Sir Harold Evans, former editor of the Sunday Times and Times, branded the Met's move "ridiculous". Writing in today's Observer, he says: "I cannot believe that the attorney general will let this case of uniformed bullying go forward" and claimed that "without the ability and determination of the press to protect sources many wrongs would go undetected and unpunished".

Evans told the Observer the Official Secrets Act was never intended for such use. "This is a cavalier abuse of an act intended to protect national security, not to cover up negligence and corruption, least of all to justify an assault on the very newspaper that exposed the original crime while the police, politicians and the press walked by."

John Cooper, a leading human rights lawyer and visiting professor at Cardiff University, echoed Evans's concerns. "In my view this is a misuse of the 1989 act," Cooper said. "Fundamentally the act was designed to prevent espionage. In extreme cases it can be used to prevent police officers tipping off criminals about police investigations or from selling their stories. In this instance none of this is suggested, and many believe what was done was in the public interest."

Cooper added: "The police action is very likely to conflict with article 10 of the European Convention on Human Rights, which protects freedom of speech."

Scotland Yard yesterday defended its attempt to force the paper to reveal its confidential sources, claiming it was important to preserve the integrity of its high-profile investigation into phone hacking, Operation Weeting.

"Operation Weeting is one of the MPS's most high-profile and sensitive investigations, so of course we should take concerns of leaks seriously to ensure that public interest is protected by ensuring there is no further potential compromise," the Met said in a statement.

The police are said to be seeking the source of the Guardian's report disclosing that the mobile phone of murdered teenager Milly Dowler had been hacked.

The Met said it was not seeking to use the law "to prevent whistle blowing or investigative journalism that is in the public interest".

"We pay tribute to the Guardian's unwavering determination to expose the hacking scandal and their challenge around the initial police response," it said.

"We also recognise the important public interest of whistle blowing and investigative reporting. However, neither is apparent in this case. This is an investigation into the alleged gratuitous release of information that is not in the public interest."

Guardian editor Alan Rusbridger strongly condemned the move as "vindictive and disproportionate", and said the paper would resist it "to the utmost".

A Guardian reporter, Amelia Hill, has been interviewed under caution by Scotland Yard over the alleged leaks. A 51-year-old detective constable was arrested and bailed last month in connection with the investigation.