Officers this evening (Tuesday, July 21) appealed for the public's help to locate Ryan Byrne, who is wanted on recall to prison.
Police said they were informed by the prison service on Friday (July 17) that the 34-year-old had been released "in error" from Wandsworth Prison.
Mr Byrne is described as a white man, 5ft 11ins, of medium build, with blue eyes and a goatee beard.
Byrne is believed to have been in Wardour Street, Westminster, on Saturday (July 18), and is also thought to have been to the north-west London area.
Anyone who has seen him or has any information regarding his whereabouts is asked to call police on 101.
A spokeswoman for the Met said on Tuesday evening it could not give any details at this stage of why Mr Byrne had been jailed in the first place or what his links were to the borough of Hammersmith and Fulham.