Scotland Yard has issued an urgent appeal to trace a "dangerous" man called Daniel Sonnex in relation to the murders of two French students in London.

"Sonnex is considered to be a dangerous man. Police advise members of the public not to approach him directly but to ring 999 if you see him," a spokesman said.

The badly-burned bodies of Laurent Bonomo and Gabriel Ferez were found after an explosion at a rented bedsit in New Cross, south London, on June 29. Mr Bonomo had been stabbed nearly 200 times while Mr Ferez had suffered nearly 50 knife wounds.

Sonnex, 23, who is also known as Dano, is believed to have connections close to New Cross but police said he could be anywhere.

Detective Chief Inspector Mick Duthie, of the Homicide and Serious Crime Command, said: "Anyone who thinks they might know where Sonnex is or has any information regarding him should get in touch immediately.

"You can call the Incident Room at Sutton on 020 8721 4155 or, if you want to stay anonymous, you can call Crimestoppers on 0800 555 111."

Sonnex is described as white, 6ft 3in and of proportionate build. He has brown eyes and short dark hair which is believed to be shorter than in the picture issued by police.

A police statement said: "We are appealing urgently for any information regarding the whereabouts of a south London man in connection with the murders of Laurent Bonomo and Gabriel Ferez in New Cross on Sunday 29 June."

Nigel Farmer, 33, of no fixed address, appeared at Greenwich Magistrates' Court on Thursday accused of the double murder.

Farmer, who is also accused of arson and attempting to pervert the course of justice, was remanded in custody until October 16 when he will appear at the Old Bailey. A 35-year-old man and a 25-year-old woman who were arrested yesterday in Streatham, south London, remain in police custody.