Labour MPs are demanding Theresa May intervene personally to stem the rise of gun and knife deaths in London, accusing her of being “absent while violent crime surges”.

More than 40 MPs in the capital have signed a letter demanding a face-to-face meeting, amid attacks on both the prime minister and Sadiq Khan, the London mayor, for their lack of involvement in the crisis.

The prime minister was criticised after it emerged she visited east London on Thursday to open a new office for the local Conservative party and to campaign for next month’s local council elections.

The office, in Waltham Forest, is close to the scenes of three violent deaths since the start of the year – but Ms May is understood to have not visited the sites, nor spoken to police.

In the letter, Labour MPs urged the prime minister to recognise that “communities are crying out for national leadership on this issue”.

The letter linked the deaths directly to “funding cuts of £1bn” to the Metropolitan Police, alleged that “probation and prisons are in chaos” and that youth services had been “cut to the bone”.

Mr Khan has also been criticised for his lack of response to the killings, and for failing to meet any victims or visit the murder scenes. The MPs pointed out that 75 per cent of Met funding comes from the government.

“We are calling on you, the prime minister and home secretary, to urgently meet with us, along with the mayor, to discuss what more must be done to make our city safer,” the letter reads.

“We need a police force with the resources to provide reassurance to communities, do the necessary prevention work and catch those who commit crimes.”

The letter adds: “Social media is a key factor, glorifying and amplifying violence. Social media companies must take down videos and posts that are fuelling the rise in violent crime.

“On all these issues, we need urgent action from the government. It is not good enough simply to ignore the impact cuts have had on communities. Ministers cannot bury their heads in the sand.”

The letter has been coordinated by Wes Streeting, Labour MP for Ilford North, and signed by both frontbenchers and backbenchers, including Jeremy Corbyn.

There have been more than 50 murders in the capital in just the first three months of the year – forcing Mr Khan to deny the police “have lost control of crime in London”.

Police patrols have been stepped up and officers are using stop-and-search powers to seize weapons, the Met says.

Stella Creasy, Labour MP for Walthamstow, criticised Ms May's priorities on Twitter, telling her: “If you can come to our borough looking for votes as you did today... the least you can do is hear our call for help to tackle the violent crime we are experiencing.”

But Jo Johnson, the minister for London, criticised Mr Khan for failing to focus on the problem, saying: “Londoners deserve to feel safe on the streets and that is why the government has given the [Met] additional funds again this year.