An alleged killer stabbed a man to death before using the bloodstained blade to attack a teenage boy, a court has heard.

Joe Gynane, of Wimbledon, is accused of murdering Mohamed Elmi, 37, with a large kitchen knife in a "short but deadly assault" in the doorway of a Soho pub in the early hours of Sunday, March 3 this year.

Mr Elmi died in hospital several days after he was repeatedly knifed outside the Coach and Horses bar, the Old Bailey heard on Monday.

Several hours later, Gynane, 34, allegedly stabbed and seriously injured a 16-year-old boy, who cannot be named for legal reasons, in an alleyway off the Tottenham Court Road.

Prosecutor Gareth Patterson QC told jurors: "A few months ago, on the morning of Sunday March 3, this defendant launched two violent knife attacks on the streets of this city.

"In his first knife attack he fatally stabbed a man called Mohamed Elmi in Soho.

"In a short but deadly assault in the doorway of a pub he stabbed him repeatedly using a large kitchen knife."

Gynane and Mr Elmi had spent parts of the early morning together walking around Soho smoking and allegedly taking drugs with a group of people, the court heard.

Mr Patterson went on: "It looks as though he and others around him are taking drugs.

"At times, his movement on his feet suggest he was under the influence of drugs."

Gynane denies murder and causing grievous bodily harm with intent.