Cuts to the police counter-terror budget will not put lives at risk, says the Home Office's top civil servant.
Sir David Normington told MPs that counter-terrorism grants had increased sharply since 2006 and police chiefs had agreed efficiencies could be found.
He said he would not have been part of a "dangerous" spending settlement.
But he told the home affairs committee some police forces would find other cuts "tough" - and some were better prepared than others.
In his final appearance before the committee Sir David, who is retiring as permanent secretary at the Home Office, was pressed on the impact of spending cuts on police forces.
Labour MP David Winnick asked how a 10% real terms cut in the police's counter terrorism budget by 2014-5 could be considered "wise" in light of the terrorism threat.
Sir David said the 10% cut was less than the cuts faced by police generally and, as police counter-terrorism grants had risen "very sharply" since 2006, it had been agreed with Assistant Commissioner John Yates - who is in charge of counter-terrorism at the Metropolitan Police - that those efficiencies could be made.
"I am absolutely confident that we are providing the money, that the 10% reduction does not seriously impact on our ability to counter terrorism," he said.
Asked whether the cuts could cost lives, he said: "I'm confident that these reductions can be made without making an impact on lives and so on. We wouldn't, I wouldn't, have been party to a settlement which cut the counter terrorism budget in a way that was dangerous."
The Home Office will cut police funding by 20% over four years and various forces have warned of front-line job losses.
MPs on the committee repeatedly pressed Sir David on how many police jobs were expected to go - and whether there would be an impact on crime.
He said he did not know how many jobs would go as chief constables would take the "final decision" on job numbers - alongside their police authorities - and the numbers would differ from force to force: "All of them start from the position they will try to maintain the front line service."
"It is very difficult, it is not straightforward and some forces have been planning for it for quite some time, some have not and it's going to be quite tough for them."
The Association of Chief Police Officers says cuts are "front-loaded" and will mean a 6% cut in the first year, 8% in the second year and 4% cuts in the final two years - a total of 22%.
Sir David said the "front-loading" of cuts "makes it tougher" but were a result of negotiations with the Treasury.
Labour MP Stephen McCabe said chief constables had been telling the committee they were not expecting "this level of cuts or this time scale".
Sir David said: "I believe they have been preparing for very serious reductions, I accept that they were not expecting the scale of reductions in years one and two."
He said a freeze on police pay from next September was "worth £350m and that does ease the position a bit in the first two years".
Despite leaked Home Office advice to then Home Secretary Jacqui Smith in 2008, crime had not risen during the recession, he told MPs.
"We have not done similar work and we are not expecting crime to rise as a result of these reductions - it is an expectation that every force will be seeking to organise its services to try and maintain its impact on crime," he added.
Mr McCabe said that was a "mealy mouthed" answer but Sir David said there was "quite a complex relationship between police numbers and whether crime rises or falls and one of the key issues is how you deploy your police numbers".
He said that over the course of four years from April 6,500 Home Office jobs - and those at its agencies - would go, of which 650 would be from the core department. Most Home Office staff were at the UK Border Agency, he added. In addition the number of jobs would be cut by between 2,500 and 2,600 this year.
He was also challenged about Home Office spending in other areas - including consultants, management courses and UK Border Agency Lin Homer's £208,000 salary.
Asked by Tory MP Aidan Burley if she should consider taking a pay cut as a signal of the end of "public sector excess", Sir David said it was a tough job and there was not a queue of people waiting to do it: "She's worth that amount of money, she's done a great job," he said.