Ofsted inspectors will now be looking at how London schools are dealing with the threat on knife crime in its reports.

Mike Sheridan, the education watchdog's regional director for London, said knife crime is a "sickening concern" for young people, families and communities, and that Ofsted wants to support schools in their work to safeguard children.

The school's inspectorate has commissioned a survey, which is being sent to 700 schools and colleges in the capital, asking them for their experiences of knife crime.

The move comes amid growing concerns about a violent crimewave hitting London.

So far this year, the Metropolitan Police have launched more than 60 murder investigations, with at least 39 involving knives, and many victims have been young people.

In a blog, first reported by the Times Educational Supplement (TES), Mr Sheridan said: "Knife crime is a stain on our society. It is a sickening concern for young people, their families and entire communities.

"In recent times, it seems like not a day goes by without heart-wrenching headlines telling of yet another young life, tragically taken too soon. I, like many others, simply cannot sit by without trying to help.

"This is why we commissioned a survey to look at how schools in the capital are safeguarding pupils against the threat of knife crime on their premises, and how pupils are being educated on the dangers of carrying a weapon."

Mr Sheridan said schools, colleges and other agencies working with young people "have an absolutely vital role to play in protecting children from knife crime" and that Ofsted "is determined to support this important work".

He added: "As part of this work, we are asking all headteachers of maintained secondaries and academies, pupil referral units and some principals of further education colleges in London to respond to a questionnaire about their experience of knife crime and related issues."

Mr Sheridan said the responses will be used to inform the watchdog's research and will not be used to make judgments about individual schools.

Schools will be able to choose to give information anonymously.

"We want to understand what teachers and leaders are doing to protect their young people from knife crime, so that we can learn from it and help other schools and colleges in developing their own strategies."

Ofsted is also carrying out focus groups with parents of children who have been affected by knife crime, Mr Sheridan said, adding that it hoped the findings will also benefit schools in other parts of the country.