The former US police chief Bill Bratton has said he is a "progressive" who can lead British policing out of "crisis", reduce crime despite budget cuts, and bring about "transformational" change in the aftermath of last week's UK riots.

In an interview with the Guardian, Bratton said he was "seriously" interested in the vacant post of commissioner of the Metropolitan police but that the home secretary, Theresa May, had been "adamant" in banning foreign nationals from applying.

Bratton – credited with turning around troubled police departments in New York and Los Angeles – is understood to have been David Cameron's choice to run Scotland Yard. Instead he will advise the prime minister on gangs and crime after the Home Office insisted that candidates must be British.

According to Whitehall sources, Bratton has also told friends that he was so keen to take the job he would be prepared to take British citizenship if it made the difference. Cameron's courting of Bratton continued to provoke criticism by senior British officers on Sunday.

Cameron will say in a speech today about the riots that Britain has undergone a "slow-motion moral collapse". The Labour leader, Ed Miliband, meanwhile will make a rival speech denouncing as "gimmicks" ideas put forward by senior Tories over the weekend to clamp down on crime with "zero tolerance".

The series of rows between the Tories and senior police officers intensified yesterday. They are disputing where the blame lies for the loss of control of the streets to looters, who deserves the credit for quelling the riots, and whether budget cuts will endanger public safety.

Among the day's developments:

• Chris Sims, chief constable of West Midlands police, criticised "empty slogans" after Cameron's remarks about a "zero tolerance" of crime – a theory Bratton used in New York. In a statement, Sims said: "I continue to work with the police authority to develop a policing response that is consistent with available good practice but is not slavishly adopting empty slogans."

• Theresa May, the home secretary, said it was her job to tell police chiefs "what the public want them to do". In his Guardian interview, Bratton hits out at those opposing foreign expertise to help UK policing and warns against being "parochial".

• The London mayor, Boris Johnson, said he would continue to fight for more police officers.

The appointment of Bratton as a consultant on gangs by the prime minister was attacked over the weekend by Sir Hugh Orde, president of the Association of Chief Police Officers.

In a swipe at Orde, who has dismissed the call for foreign police chiefs as "simply stupid", Bratton said Orde himself was successful as an Englishman coming in as an outsider to run the police in Northern Ireland. "I find it ironical, the hue and cry about outsiders," Bratton said.

He added that US police chiefs would be fired if they spoke out against politicians in the same way as Britain's top police officers have done.

Bratton's remarks are his most extensive yet on how his experience could, he claimed, make British streets safer, and will be seen by some as a job application.

He told the Guardian he had been "an outsider" when he took over police departments in the US and the situation with the Met "mirrors" those he inherited in New York and LA police departments.

The similarities were a leadership stepping down amid a corruption scandal, disorder on the streets, rows with politicians and community concerns about policing.

Bratton said: "The Met is having its share of issues and leadership crises, certainly. It is a mirror image of when I went into the NYPD and LAPD, and both those cities turned out quite well. I've been an outsider in every department I've worked in. Bureaucrats change processes, leaders change culture. I think of myself as a transformational leader who changes cultures."

Bratton said US police chiefs had shown their British counterparts the way, securing large falls in crime despite facing falling budgets. In LA, where he stepped down as police chief in 2009, despite high unemployment and a 15% budget cut, crime is down by 10%.

Bratton said: "You can run around saying, 'The sky is falling in, the sky is falling in,' or you actually do something about it. You have to play the hand you're dealt. I've always dealt initially with budget cuts.

"Out of crisis come opportunities. If you want to speed up the process of change, nothing does it better than a good old crisis."

Bratton said the chance to become Met commissioner was attractive: "If it was open to people other than British citizens, it would be something I would seriously consider. I understand the home secretary is adamant in opposing that."

Bratton declared he was steeped in the traditions of British policing and insisted he could change its culture. He said human rights were at the heart of his thinking: "Britain is the birthplace of democratic policing. Robert Peel's nine principles [of policing] shaped my thinking."

But it had to learn from elsewhere, he said: "Anyone who looks only inwards is not going to be as successful as someone who looks outside, the world over. It's a big world out there."

He said his track record demonstrated his toughness on crime. He told the Guardian he was a "progressive", pointing out that he hired more people from ethnic minorities, women, gay people and transvestite people to make the police forces he ran reflect the communities they serve.

The rebellion by British police chiefs spread , with fresh annoyance being triggered by Cameron telling a Sunday newspaper he wanted "zero tolerance" policing adopted on Britain's streets.

The courts opened their doors on a Sunday for the first time as the justice system continued to struggle to process suspected looters and rioters.

The police surge in numbers following the rioting was maintained , but unless there is further trouble or intelligence of fresh disorder, some areas will start reducing the officers out on the street on Monday .

British Police chiefs who thought government criticism was limited to the Met's handling of the outbreak of disorder in London, now feel the attack has spread to the reaction to force in the West Midlands and Greater Manchester.

On Sunday Chief Constable Sims said: "I look forward to being held to account for the decisions I have made over the past week which I believe were consistent with the available information and resources.

I am proud of how quickly the force adopted new tactics to this unprecedented challenge."

Amid stiff sentences being handed out to rioters and looters, Sims called for compassion not to be lost: "Sentencing is justifiably harsh but we must not at this time abandon all compassion for some of our very damaged young people who have been caught up in these incidents."

Tim Godwin, acting commissioner of the Met, said the criticism had led to "upset" among his command team and officers on the ground.

Andy Trotter, chief constable of British Transport police and a public order expert who is seriously considering applying for the Met commissionership, said he did not believe government claims that budget cuts would not damage the police: "We cannot pretend that the scale of cuts we face will not impact on the frontline of policing.

"It is simply not possible."