British police said on Saturday they were scouring hours of closed-circuit TV recordings to find an asylum seeker sentenced for sexual assault who was mistakenly released from prison.

Ethiopian national Hadush Gerberslasie Kebatu, 38, was “last seen in the London area”, Essex Police said on Saturday, adding that officers from three separate forces were working together in the investigation.

Kebatu came to national attention after his case triggered a wave of anti-migrant protests in London and other cities in recent months. He was sentenced in September to 12 months in prison for five offences, including the sexual assault of a 14-year-old girl in July in Epping, on the outskirts of London, just over a week after he had arrived in England by boat.

Authorities said they were alerted on Friday afternoon that Kebatu was released by mistake at a prison in Chelmsford, Essex, and was seen catching a train there. British media reported that he was wrongly categorised as a prisoner due to be released, instead of being sent to an immigration detention centre.

“Officers worked throughout the night to track his movements, including scouring hours of CCTV footage, and this work continues today,” a police statement said.