Simmering tensions at Rupert Murdoch's News Corporation burst into the open on Monday when a senior Sun journalist voiced unease that the company's powerful management and standards committee had handed information to the police that has led to the arrests of nine journalists from the tabloid over the last three weeks.

Trevor Kavanagh, the associate editor and former political editor, took to the airwaves to give voice to anger and frustration emanating from the Sun's newsroom – which in turn prompted the MSC to defend the anti-corruption investigation, and the Metropolitan police its tactics.

The Sun veteran, for years a close confidant of Rupert Murdoch, told Radio 4 that "there is unease about the way that some of the best journalists in Fleet Street have ended up being arrested on evidence that the MSC has handed to the police".

In another interview, on Radio 5 Live, he accused "certain parts of the company" of "boasting that they are sending information to police that has put these people I have just described into police cells".

MSC sources responded by rejecting the characterisation of it boasting about its actions, saying it had made no public statements about its part in the arrests. The committee, run from separate offices near the Sun but reporting to executives in New York, believes it has little choice but to co-operate with the Elveden police investigation into corrupt payments to public officials because of the risk News Corporation would otherwise be accused of obstructing the course of justice.

Kavanagh said the mood on the Sun was "despondent", and there was "a feeling of being under siege". He added: "There has never been a bigger crisis than this."

Kavanagh also took aim at the Metropolitan police, saying that Sun journalists were being "needlessly dragged from their beds in dawn raids" with "up to 20 officers at a time" ripping up floor boards – tactics that he described as treating "journalists like members of an organised crime gang". Kavanagh also said that some of the police had been diverted from other jobs, such as protecting the Olympics from a "mass suicide attack".

But on Monday the Met defended its handling of the investigation, saying that it was justified by "the seriousness of the allegations and significant number of victims". It said that no other major investigations had been compromised by the concentration of resources.

Tom Watson, the Labour MP who has spearheaded the Commons inquiries into phone-hacking, laid the blame on the police tactics on News International.

Referring to a recent court case in which the company admitted that senior executives and directors had lied to police and destroyed evidence, he wrote: " It is News International's behaviour that is to blame for police having to devote immense time and resources to establish the facts. By deliberately lying to the police and trashing evidence they have made the job far more complex and expensive than it should have been."

Five senior Sun journalists were arrested on Saturday on suspicion of corruption under the Prevention of Corruption Act 1906, aiding and abetting misconduct in a public office (contrary to common law) and conspiracy in relation to both these offences. They were deputy editor Geoff Webster; the picture editor, John Edwards; the chief reporter, John Kay; the news editor, John Sturgis; and Nick Parker, chief foreign correspondent. There is no "public interest" defence as regards the 1906 act, and a payment of any size could trigger an offence.

The Met said "the seriousness of the allegations" meant it did not believe the 169 officers working on three investigations – the corrupt payments inquiry, the Operation Weeting phone-hacking investigation, and in the computer-hacking unit Tuleta – were "in any way disproportionate to the enormous task in hand".

The Met added "that no more than 10 MPS officers attended each of the home addresses of the persons arrested as part of Operation Elveden" on Saturday and that at "no stage has any [other] major investigation been compromised".

In response to Kavanagh, Watson said: "The notion that the police might politely ring up to make an appointment to see a Sun journalist for a civilised chat is far-fetched. It takes some nerve for News International, in the form of Kavanagh, to be accusing the police of wasting time and resources."

About 20 police are based in a special room at Wapping where they ask the MSC – whose members are Will Lewis, a former editor of the Daily Telegraph and News International executive, and Simon Greenberg – and its lawyers Linklaters to conduct searches of a database of an estimated 300 million emails for items of potential use to the Elveden and other inquiries. The database is held in another room, staffed by the MSC and Linklaters, who respond to police requests for information – handing over data the MSC believes is directly relevant to the police investigation. Only the identities of any alleged recipients of illegal payments are identified.

Oversight of the process is conducted by Joel Klein, a long-time Washington anti-trust lawyer, who sits on News Corp's board, and runs the company's fledgling education division, reporting to Rupert Murdoch. While Klein is briefed on the information shared with the police, Linklaters also provide weekly reports to the independent non-executive directors at News Corp, as the company seeks to demonstrate how seriously it is acting after the long failure to come to grips with the phone-hacking affair.

Elveden's remit is to conduct an "investigation into allegations of inappropriate payments to police and public officials" including members of the armed forces and prison officers. Those familiar with the workings of the inquiry said the focus on "payments" meant that journalists should not be targeted if they had simply taken a police officer or other public official out to lunch.

However, it remains unclear how far the allegations date back, although it is understood that they are spread out over a period of some years.

Later this week Murdoch flies to London on what has been described as a scheduled visit, but which company insiders fear will rapidly become a media circus, with a not necessarily justified expectation that the veteran proprietor will take some form of action.