Police officers have marched past the Home Office's headquarters in central London in a protest over pay.

Around 15,000 off-duty officers and members of the Police Federation are set to follow Tuesday’s demonstration with a “mass queue” outside Parliament to lobby their MPs and present a petition to Number 10.

Liberal Democrat candidate for London Mayor, former Metropolitan Police deputy assistant commissioner Brian Paddick, was set to join the march against home secretary Jacqui Smith’s decision to implement a 2.5 per cent pay rise in two stages.

The union argues that this would make it worth just 1.9 per cent over the year, compared to the full 2.5 per cent which has been awarded to officers in Scotland and civilian police staff in England.

TUC general secretary Brendan Barber sent a message of “solidarity and support” to federation chairman Jan Berry, who is due to meet the home secretary after the March.

Barber said the government had made a “disastrous mistake”, but the prime minister's spokesman said the government had to take some tough decisions about last year’s settlements.

Speaking as the march prepared to set off, he said: "The position in relation to the police is as the prime minister and the home secretary have said on numerous occasions, that the government has huge admiration for the work of the police.

"But that we did face a difficult situation last year with inflation that required difficult decisions across the public sector in order to stage pay awards.

"As a result of that, inflation has gone down, whcih enabled the Bank of England to reduce interest rates last year."

But a member of the Commons home affairs committee said the government could calm police anger by permitting increases in allowances, even if it was unwilling to change its headline offer.

Labour MP Martin Salter told the BBC: “The police authorities had budgeted for 2.5 per cent so the money is in the kitty and it would be possible to use some of that money to boost the special priority payments in all sorts of different ways.

“That could be to provide a boost to the South East allowance and it could be used in other ways in different parts of the country,” he added.

“Given the money is already in the budget, to lose the confidence of the crime-fighters themselves is not clever politics and it is not right.”