The outgoing chief of London's Metropolitan Police has warned of the brewing "challenges" threatening the country's forces due to budget cuts and growing crime.

Sir Bernard Hogan-Howe, the UK's most senior policeman, leaves his role this month and said public safety is at risk due to the growing pressures facing police forces.

The government has reduced funding available for police and crime commissioners by £2.3bn ($2.87bn) since 2010 resulting in a 25% decrease in budgets. Meanwhile, violent crime has risen by 24% between 2015 and 2016.

Appearing on the BBC's The Andrew Marr Show on Sunday (5 February), Hogan-Howe said: "The big thing that's gone wrong since 2008 is that there isn't enough money.

"Obviously, when the banks went wrong in 2008, public service spending went down. So, if you looked across the UK, the number of cops has gone down from 147,000 to about 127,000.

"I'm proud of the fact that in London we're the only force in the country to have maintained our officer numbers – 32,000 cops still – but I think in the future that's going to be very, very hard because the money is still tight.

"One is because the demands on that money are getting higher with pay increases and various other things and of course, the likelihood we know that by 2020 there will be even less public spending. I think there's another £3bn to find.

"So, I think the challenges are going to be that we've seen some rises in crime and we are seeing also the amount of money available for the police will reduce."

Hogan-Howe also highlighted that increased pressure will be felt by London's rapidly increasing population, which has now eclipsed nine million.

He warned that as a result of the budget cuts, it would be inevitable that the number of police officers on the street were cut also.

"I'm not a defeatist by nature," Hogan-Howe said. "I don't think just because you have less money you have to fail.

"I think all I'm highlighting, to be fair to my successor, is that it's going to be a more challenging environment.

"We have done a lot over the last five years to make the Met more efficient and more modern. We have taken out an awful lot of things from the past that were inefficient and kept our 32,000 cops. We've got less buildings. We've got less managers.

"Sadly, you've got to do these things and there are more hard decisions to come."

When asked what those hard decisions will be, Hogan-Howe said: "The main thing is how do we find another £400m savings?

"You know, you can only make so many efficiencies so you will probably end up with less people. Seventy-odd percent of our costs are down to people, so therefore you've got to look in that area when we've already made savings in the ways I've said."