Police raids which led to the arrest of five Sun journalists have been attacked by Trevor Kavanagh, the paper's associate editor.
He told the BBC the paper's publisher - News International - was the subject of a "witch-hunt" and the investigations under way were "disproportionate".
The Met Police denied this and said the three inquiries were "complex".
The reporters were arrested in connection with alleged corrupt payments to police and others.
A Surrey Police officer, a member of the armed forces and a Ministry of Defence employee were also arrested - and all eight were released on police bail.
Talking to Radio 4's World at One programme, Mr Kavanagh said: "There are people who will stop at nothing to destroy News International.
"They will not be satisfied until the Sun is closed too."
He said using 171 police - some of whom, he alleged, had been taken off counter-terrorism duties - to work on the investigation was questionable.
He said 30 journalists had been "raided at dawn and arrested, put on police bail with indefinite limits on what they can do in terms of earning a living," adding: "I think that you have to wonder what is behind it all.
"I think a witch-hunt is not an unreasonable definition of this exercise," he claimed.
He said: "What we feel is over the top and disproportionate is the number of police involved and the number of arrests that have been made.
"No charges have been made and an awful lot of people are having their lives disrupted with dawn raids , by police squads of up to 20 at a time - which we feel is out of proportion." Police had rifled through children's underwear drawers looking for information, he went on.
He said the company was happy to co-operate with any enquiries but the reaction of the police was "over the top".
Mr Kavanagh, who stressed the Sun would not close, had earlier written about the issue in his column in the paper.
At any other time the treatment of the journalists would have caused uproar at Parliament and among civil liberty and human rights campaigners, he said.
He also said senior members of staff had been treated like "an organised gang" and insisted that the tabloid was "not a swamp that needed draining".
He said money sometimes changed hands while unearthing stories, and this had always been standard practice. The company would always consider the public interest first when a story was under consideration, he told the BBC.
He said of his colleagues: "They are very fine journalists who have used every contact they have to deliver stories in the public interest and I believe, if there were to be any charges preferred, they would make that the staunch defence that they are acting in the interests of the public, the interests of their readers and indeed the interests of journalism and newspapers generally.
"There are journalists in every other newspaper, including those leading the charge against us, who deploy exactly the same methods and procedures of trying to unearth stories which are in the public interest."
In a statement, the Met Police said: "The linked Operations Weeting, Elveden and Tuleta are extremely difficult and complex with literally millions of pieces of documentation needing to be scrutinised and examined."
It said it did not believe the level of resources devoted to the inquires was "in in any way disproportionate to the enormous task in hand".
It said 169 officers and staff were currently working on the three investigations.
Ninety-one officers were working on Operation Weeting; 61 on Operation Elveden and 16 on Operation Tuleta - this is focusing on computer hacking.
The statement continued: "The majority have come from Specialist Crime; Territorial Policing and the Directorate of Professional Standards. At no stage has any major investigation been compromised as a result of these deployments."
It said there were no more than 10 police officers attending the homes of each of those arrested on Saturday and added: "Several officers are needed for the thorough and efficient search of an address, including, where appropriate, specialist search teams."
Mr Kavanagh had also told the BBC that there was "unease" at the paper over the fact that News Corporation's Management and Standards Committee had given police information which led to the most recent arrests.
News Corporation is the parent company of News International, which runs the Sun.
"There's certainly a mood of unhappiness that the company - certain parts of the company, not News International I hasten to add, not the newspaper side of the operation - are actually boasting that they're sending information to the police," he said.
Sun editor Dominic Mohan has said he was "shocked" by the arrests but pledged to continue to lead the paper.
Those held during the raids at the weekend were arrested as part of the Operation Elveden probe into payments to police.
The BBC understands they were picture editor John Edwards, chief reporter John Kay, chief foreign correspondent Nick Parker, reporter John Sturgis and associate editor Geoff Webster.
Meanwhile, Mark Lewis, the solicitor representing alleged victims of phone hacking told the World at One, he would pursue News Corporation in the US "if appropriate".