London’s murder rate is on course to hit its highest level for more than a decade after another young person was stabbed to death on the capital’s streets after leaving a bar.

A 20-year-old man was found stabbed in Wandsworth, south-west London, early on Sunday morning and was pronounced dead just before 2am. It was the 31st stabbing death in London in the first 13 weeks of 2018. A 21-year-old man was arrested on suspicion of murder.

DCI Mark Cranwell, of the Metropolitan police, said: “Sadly, another family has been left devastated with the tragic death of a young man from an act of violence. We are appealing to anyone who was in the area to come forward.

“We know that the victim left a bar in Garratt Lane, SW18, at 1.05 and then seven minutes later he was found on Ellerton Road at the junction with Burntwood Lane. Did you see any vehicles or people acting suspiciously in this area at around 1.10? Any information you hold, no matter how small, could prove vital to our investigation.”

The first quarter of 2018 has seen 46 murders in the capital, a rate of more than three a week. If that keeps up, London could surpass 180 homicides this year, back to the levels last seen in 2005 when there were 181.

In 2017 there were 116 homicides in London, excluding the deaths in the Westminster, London Bridge and Finsbury Park terrorist attacks.

This year, according to the Metropolitan police, there were eight homicides in January, 15 in February and 22 in March.

Thirty-one of the killings so far were stabbings, four were shootings, three were due to multiple injuries, one was caused by neck compression and in five cases the postmortem results are awaited. In two other cases the cause of death is believed to be stab wounds.

The Met commissioner, Cressida Dick, mentioned social media as one of several factors in a recent newspaper interview, and police chiefs fear further damage to public safety due to falling officer numbers caused by budget cuts.

Furthermore, the spike in homicides this year has come during cold weather, with warmer weather linked by some to increased numbers of people on the streets and opportunities for disputes that escalate.

A claim over the weekend that London’s murder rate in February and March exceeded New York’s has been dismissed by police chiefs because it was based on too short a period. New York had 292 murders in 2017 and has had 50 so far this year.

A Met spokesperson said: “London remains one of the safest cities in the world. The Met is concerned at the increase in murders in London, and specialist detectives from the Met’s homicide and major crime command are investigating.

“One murder is one too many, and we are working hard with our partners to understand the increase and what we can all do to prevent these tragedies from happening in the first place.”