Sadiq Khan has condemned the “horrific” spate of stabbings and warned criminals face the “full force of the law” after four people were knifed to death in one night.

The stabbings, which all occurred within hours of each other as most people were enjoying New Year’s festivities, are not believed to be connected.

Four people were killed in the violence, which happened in south, east and north London, and a fifth is in a critical condition in hospital.

In a statement issued following the police appeal, Mr Khan said his thoughts were with the families of those killed.

The Mayor said: "The police have today assured me that everything is being done to bring to justice those responsible for these appalling acts of violence.

"The police were out in force helping people enjoy our city's fantastic celebrations last night, and I thank them. However, it is horrific that knife crime has claimed another four young lives as the New Year begins.

"We will work tirelessly in 2018 and beyond to stamp out this scourge.

"I want to be absolutely clear - if you use a knife the full force of the law will be brought down on you. You will be caught and prosecuted."

At his last Mayor's Question Time, Mr Khan had said: "Every death on the streets of London is an utter tragedy and I'm deeply concerned about the rise in knife crime.

"I am supporting the delivery of community-led solutions and delivering interventions at critical points to offer real opportunities to exit offending behaviour as well as coming down hard on those who habitually carry knives."

Three of the victims were killed on New Year's Eve and a fourth in the early hours of New Year's Day, Scotland Yard said.

Detectives investigating the killings, described as acts of "senseless violence", are appealing for information from the public.

The first killing happened at around 11.30am. A teen, aged 18, died in hospital after being knifed in Larmans Road, Enfield. At 7.30pm in Memorial Avenue, West Ham, a 20-year-old man was fatally stabbed.

At around 10.40pm, a third man – aged just 17 – died after being stabbed in Norwood Road, Tulse Hill. And in the early hours of January 1, at around 2.30am, a 20-year-old man was fatally stabbed in Bartholomew Court, Old Street. A second male, aged in his 20s, was taken to hospital suffering critical stab injuries.

Five males have been arrested in connection with the murder in Enfield.

Commander Neil Jerome, of the Met's Territorial Policing Command, said: "It is heart-breaking that, at a time when so many of us are contemplating what lies ahead in 2018, four families are dealing with the grief of losing a loved one to senseless violence and the callous use of knives as lethal weapons."

He said police are working "tirelessly" to catch those responsible for "such despicable acts of violence" and said the Met is determined to tackle London's knife crime - especially among young people.

Commander Jerome appealed for information on the attacks or about anyone who routinely carries a knife.

"If you've hesitated to do so before, then these four tragic deaths at the start of a new year may persuade you to act now to make London safer for your family and friends in 2018," he said.

Anyone with information can call police on 101 or, to remain anonymous, Crimestoppers on 0800 555 111 or crimestoppers-uk.org.

