Police fear they'll be left to pick up the tab for the riots

David Cameron meets Acting Borough Commander Superintendent Jo Oakley on a visit to Croydon (GETTY IMAGES)

Police forces across the country may have to pick up part of the multimillion-pound bill for dealing with last week's riots despite a pledge by David Cameron that the Treasury would "stand behind" them.

The Home Office is refusing to guarantee that it will cover all the money spent by the police on overtime, equipment and cancelled leave as they struggled to control the rioting in London, Manchester, Birmingham and other British cities.

Senior officers and police authorities are concerned that the Government will try to take the extra costs out of their already stretched police budgets rather than using the Treasury reserve.

They are also furious with Theresa May, the Home Secretary, describing her latest remarks on the riots as "ill-informed or wilfully inaccurate" after she used them to justify plans to push through directly elected police commissioners.

The Association of Police Authorities is expected today to give authorities across the country initial estimates of the bill for the riots.

The bill to the Metropolitan Police is certain to be the largest and could exceed £10m. Nottinghamshire Police has said it faces a bill of £1.2m for the extra policing and the repair costs to five police stations that came under attack in the riots. Leicestershire Police said last week that it was likely to have spent at least £250,000 on its operation, mainly in overtime.

Shortly after the riots David Cameron told the House of Commons: "The Treasury is standing ready to assist police forces. Clearly, the bill for the Metropolitan police force for the past few days will be large and, if they continue to deploy in those numbers, it will get larger and the Treasury will stand behind that."

But yesterday the Home Office appeared to be backtracking. In a statement it would say only: "There is an established system of special grants in place to support forces where they face unexpected or exceptional costs. It is up to individual forces if they wish to apply for a special grant and all applications will be considered."

Senior officers point out that this fund is discretionary and is normally used to cover public events like party political conferences, demonstrations and other unbudgeted policing costs.

They say that their past experiences of the fund is that they never recoup the full amount they claim for and are concerned that the Home Office will try to make them pay for significant parts of the bill.