An extra £27.8 million funding was announced today for the Metropolitan Police after the outgoing Commissioner warned the force faces NHS-style “rationing” of services.

Mayor Sadiq Khan said the extra money would help maintain police numbers at 31,000 just days after Sir Bernard Hogan-Howe warned the force would struggle to cope if they dropped below 30,000.

However, Mr Khan has already admitted he has only committed enough cash this year to maintain the force’s current strength – which is 1,000 officers lower than the strategic target.

It comes just days before Home Secretary Amber Rudd and the Mayor decide who will be the next Met Commissioner, with Cressida Dick, the former head of counter-terrorism operations at the Met, the favourite.

Mr Khan told the London Assembly: “My first priority is keeping Londoners safe and that means keeping police officer numbers as high as possible.

“I’ve done everything possible to protect police numbers in this budget – the Government must now do its part too.”

The Mayor also announced an extra £250,000 for a major new campaign against knife crime amid a surge in teenage stabbings.

He has allocated £620 million to policing this year, which along with £1.9 billion from the Home Office and £420 million from the Government, brings the overall budget this year to £3 billion.

But it comes amid fears that up to £700 million could be cut from Scotland Yard’s central Home Office grant as a result of a shake-up of police funding.

Under the changes, money given to London could be diverted to regional forces under a new funding formula designed to reduce alleged imbalances in the way cash is currently allocated.

It would come on top of the £600 million of cuts already made since 2013, with a further £400 million to come by 2020.

City Hall aides also said he planned to do “everything possible” to stick to the strategic target of 32,000 police officers across London, although it currently stands at 31,000 officers.

But critics suggested Mr Khan could be doing more by putting even more cash into policing rather than setting up a new capital reserves fund.

Liberal Democrat Caroline Pidgeon said: “However much Sadiq Khan wants to peddle the claim that he is doing everything possible to support the Met the reality is very different.

“Instead of making the Met his number one priority his budget is setting up a massive capital reserve to fund a series of projects which he has yet to even clarify.

“The Mayor should be concentrating solely on keeping Londoners safe he is instead creating an election war chest.”

In December, Mr Khan announced plans to increase his share of council tax bills by an average £4 a year in April to help maintain police numbers.

Sir Bernard warned last week that under planned cuts the Met could lose thousands of officers, the remainder would be slower to respond, and this could lead to a surge in crime rates.