Britain's most senior police officer today warned the capital faces losing another 3,000 officers as the force faces 'unprecedented' challenges.

Cressida Dick, Met Police Commissioner, said the force is facing £400million of cuts over the next three years.

She said a spike in crime combined with the surge in terror attacks and the funding squeeze has resulted in an 'unprecedented' challenge for the force.  

And she said the force will have to make 'ruthless' decisions about what crime and preventative work to prioritise as it faces the loss of more officers.

Appearing before the Home Affairs Select Committee in Parliament, Commissioner Dick said the force - which covers counter terrorism as well as policing in London - faces losing a tenth of its officers by 2020.  She told MPs: 'Our planning assumption at the moment is that if (the funding cut is) £400million, and things stay pretty  much as we see them, we will go down to somewhere between 27,000 and 28,000 police officers.

'We are currently bobbing around at over 30,000 which is much less than we have been at our peak.'

In a grave assessment, she said the loss of yet more officers as recorded crime jumped 13 per cent in the past year would place a strain on the force. The police chief said: 'It doesn't feel me with any joy at all.

'I do think it is genuinely unprecedented, certainly in my policing time, to have crime going up as it is, violent crime going up as it is, and the threat of terrorism as it is, calls going up as they are.

'And complexity - a lot of what we are being asked to deal with for example organised crime, child sexual exploitation...this does all feel unprecedented.'

She said police will have to continue to try to find fresh savings and efficiencies to cope with their squeezed budget.

'If we go down to that level we will absolutely have to look at whether we can be front footed as we would like to be '

She added: 'We'll have to be really ruthless about some demands.'

The Met Police Commissioner said a 'Herculean effort' by her officers had stemmed the recent rise of violent crime.

But she warned that the four terror attacks in London and Manchester this year - and the seven foiled in seven month - have left counter terrorism officers on a relentless cycle.

She said: 'That has put a huge burden on the organisation', adding: 'The tempo at the moment with the counter terrorism command is a feeling of about 30 per cent more workload - that's on the investigative and intelligence side.'

The Commissioner added: 'It is putting a considerable strain on the organisation and on policing more generally. She told MPs that if the Met Police is given extra cash she would use it to beef up the force's intelligence and preventative work, and keep bobbies on the beat.

But as her budget is squeezed she warned that the Met will not be as 'front-footed' as she would like it to be, and have to cut back on preventative work.

Crime in England and Wales soared by 13 per cent in a year with an even bigger rise in violent offences including knife crime and sexual offences.

Forces registered 5.2 million crimes in the year to the end of June, which was up by 13 per cent on the previous 12 months.

The number of violent crimes rose from 1,033,719 cases the previous year to 1,229,260 cases this year.

There was an 19 per cent increase in the number of sexual offences recorded in England and Wales, up to 129,700 on the previous year.