A kidney dialysis patient is missing and could die within 24 hours unless he is found, police have said.
Phu Chan Luong, 46, who also answers to Chan Luong, failed to attend a specialist medical unit after he was released from hospital seven days ago.
Mr Luong, from Vietnam, who is an occasional rough sleeper in Covent Garden in central London, was last seen in Paddington on 28 May.
He is described as being 5ft 6in (1.67m), of stocky build and clean-shaven.
He has cropped hair.
A Metropolitan Police spokeswoman said: "This is a particularly sad case, as if we do not find him within 24 hours he may die."
Police have asked anybody who has seen him to contact Marylebone police station.