Rupert Murdoch's British newspaper The Sun says police swoops on its journalists are part of a "witch-hunt" that has left Britain behind former Soviet states on press freedom.
Days before Murdoch was due to fly in to reassure staff that he would not close the paper, associate editor Trevor Kavanagh said in an editorial on Monday that police were treating staff "like members of an organised crime gang".
"The Sun is not a 'swamp' that needs draining," wrote Kavanagh, who was its political editor from 1984 to 2005, a time when Britain's biggest-selling paper boasted it could swing election results.
"Nor are those other great News International titles, The Times and The Sunday Times.
"Yet in what would at any other time cause uproar in parliament and among civil liberty and human rights campaigners, its journalists are being treated like members of an organised crime gang."
Police arrested five senior Sun journalists on Saturday on suspicion of bribing police and public officials for information, in a new blow for Murdoch's US-based News Corporation.
Twenty-one people have now been arrested in the inquiry, plus 17 in a separate inquiry into the hacking of mobile phone voicemails.
The hacking scandal prompted Murdoch to shut The Sun's weekly sister title the News of the World in July, with the loss of hundreds of jobs.
Kavanagh said the investigation into corruption and phone hacking was the "the biggest police operation in British criminal history - bigger even than the Pan Am Lockerbie murder probe".
He also accused police of carrying out pointless raids on journalists' homes, instead of calling them in for appointments.
"Wives and children have been humiliated as up to 20 officers at a time rip up floorboards and sift through intimate possessions, love letters and entirely private documents," Kavanagh wrote.
Kavanagh said it was no surprise that Britain had dropped nine places to 28th in a Reporters Without Borders Press freedom index, behind Poland, Estonia and Slovakia.
The Sun sells just over 2.5 million copies a day.