You couldn't make it up: Sun staff hope Strasbourg can save them from Murdoch

Journalists set to claim that News International was wrong to disclose their sources to police

The crisis in Rupert Murdoch's news empire deepened last night when Sun journalists began planning legal action against their employer with the help of two things they have previously shunned – the Human Rights Act and the National Union of Journalists.

Several senior journalists have contacted the NUJ – to which they do not belong because News International has its own staff organisation – seeking its help in putting together a case claiming that the parent company has breached their right to freedom of expression by passing information about their sources to the Metropolitan Police.

Five Sun journalists – its deputy editor, chief reporter, chief foreign correspondent, deputy news editor and picture editor (and two Ministry of Defence officials and a Surrey police officer) – were arrested on Saturday by the Met's Operation Elveden into bribery of public officials after receiving information from New Corp's Management and Standards Committee.

The paper's staff have been fuming at what they consider to be a betrayal by their bosses, and yesterday The Times entered the fray by publishing an article by the leading human rights lawyer Geoffrey Robertson suggesting that the MSC and police's behaviour threatens press freedom by blowing the identities of possible whistleblowers. The QC wrote: "If journalists cannot promise anonymity to sources and keep that solemn promise, there would be a lot less news and what there was would be less reliable. So, on what basis can a journalist's employer, without the journalist's permission (let alone the agreement of the source) squeal on them to the police?"

The NUJ is looking into whether the action breaches Article 10 of the European Convention on Human Rights – which has been heavily criticised by Sun journalists, including one of the arrested men, Fergus Shanahan.

Michelle Stanistreet, general secretary, said: "We have been approached by journalists from the Sun. We are exploring a number of ways to support them, including discussing legal redress."

News International journalists have suggested that Sun executives and reporters were being questioned about trivial matters such as a £50 pizza bill for two officers. However, it was reported last night that the investigation is looking into claims that some police were paid retainers of up to £10,000 to provide information.

Sources close to Operation Elveden said: "This is not about expenses, this is an investigation into serious suspected criminality over a sustained period. It involves regular cash payments totalling tens of thousands of pounds a year for several years to public officials, some of whom were effectively on retainers to provide information."

Mr Murdoch is expected to jet into Britain today or tomorrow to take personal charge of the growing crisis. News Corp executives in New York are thought to be keen to jettison the troublesome British newspapers.

The Sun says: The usual editorial line

'I am happy to point out the cases where the Act has been used to right a real wrong... Except that I can't think of any'

Jane Moore, 27 April 2011

'Soft judges must not put the human rights of dangerous fanatics above the right of decent citizens to live in safety'

Trevor Kavanagh, 28 may 2007

'We'd love to see Britain ignoring orders from Strasbourg judges that stop us deporting foreign killers'

Sun editorial, 21 September 2011

'How truly awful ... Is belonging to Europe a price worth paying for allowing creeps like this to hide behind the Human Rights Act?'

Kelvin MacKenzie, 6 November 2008