The killing is the 30th teenage homicide in the capital this year - a new record.

Police were called to Philpotts Farm Open Space in Yiewsley at 7.30pm on Thursday, where the boy was found suffering from a stab wound.

He was pronounced dead at the scene at 8.25pm.

Detectives say his next of kin have been informed. Formal identification has yet to take place and a post-mortem examination will be held in due course.

The stabbing occurred less than an hour after another in the south of the capital, which claimed the life of a 15-year-old boy.

Police were called to Ashburton Park, Croydon, shortly after 7pm and gave first aid to the boy before the ambulance service arrived. The teenager was pronounced dead at 7.36pm.

A boy, aged 15, has been arrested on suspicion of murder in relation to the Croydon attack.

The Metropolitan Police said it was too early to say whether the two killings, more than 20 miles apart, were linked.

Met Police Commander Alex Murray said: "I am deeply saddened by every single homicide this year, and greatly concerned by those that have been teenage killings. Each one is a tragedy leaving behind heartbroken families and distressed communities.

"My thoughts are with the victims and all those impacted. They are not statistics, not just numbers, they all have families, and they all should have had their lives ahead of them.

"They and their families have been robbed of something precious and we should all be doing everything we can to stop this," he said.

He added that the police were devoting "huge resources" to preventing homicides and said the Met was not "complacent" about knife crime.

Speaking at a press conference on Friday, Commander Murray insisted that tackling violence and youth violence is the Met Police's "number one priority in London."

He said the force has hundreds of police officers working in schools "all trying really hard to tackle violence at its causes".

He said there has been significant reductions in violence, knife crime and gun crime in recent years - but not for teenagers.

"With teenagers, we have seen an increase in homicides," he said.

"My message today, other than speaking to the families and friends of those that London has lost, is to say you cannot carry knives in London.

"This is what happens when knives are carried and we all have a role in relation to tackling knife crime."

Commander Murray also urged people to contact independent Crimestoppers to report individuals carrying knives.

Shadow home secretary Yvette Cooper said the deaths of two teenage boys in London were "devastating" as she called for further action from the government to tackle the knife crime epidemic.

She said the country needs "neighbourhood police back on the beat, stronger laws on the criminal exploitation that draws children and young people into drug and knife crime, and support for the youth services and early intervention work that keep young people safe".

Community activist Anthony King told reporters that the community needs to "partner with the Met Police and work hard and tirelessly to eradicate the issue of knife crime" and urged all parents to search their children and their bags for knives.

He said children carry knives "as a way to protect themselves" and believes the pandemic has had an effect on young people with more broken homes and more children suffering from mental health issues due to the lockdowns.

The latest incidents brings the total number of teenage killings in the capital in a calendar year to 30 - passing a previous peak of 29, set in 2008.