A man has been arrested on suspicion of murder after a shopkeeper was stabbed to death in a robbery at his newsagents.

Scotland Yard said a 44-year-old man was detained in the London borough of Harrow on Wednesday in relation to the death of 54-year-old Ravi Katharkamar.

Mr Katharkamar was knifed in the chest as he opened Marsh Food and Wine in Pinner, north-west London, on Sunday morning.

A passer-by found him collapsed inside the shop suffering from stab injuries and police were called at about 6am.

London Ambulance Service also attended but Mr Katharkamar was pronounced dead at the scene 45 minutes later.

His attacker fled with a shop till which police are still trying to find.

Describing the incident as a "vicious and unwarranted attack on a completely innocent man", Detective Chief Inspector Simon Stancombe said: "Ravi's attacker got away with a few pounds worth of coins, but he leaves behind a family utterly devastated and a close-knit community asking who could do such a thing.

"The attacker fled with a shop till - have you found this discarded or seen someone in possession of a shop till who wouldn't normally have one? Do you know someone trying to use lots of loose change since Sunday morning?