A former United Kingdom soldier facing terrorism charges who snuck out of a London prison on a food delivery truck has been captured, police say.
Daniel Abed Khalife was nabbed while riding a bicycle along a canal path west of London after a four-day manhunt.
Khalife escaped from the Wandsworth Prison kitchen on Wednesday and got outside the gates by strapping himself to the bottom of a catering truck.
Khalife, 21, was awaiting trial on charges of violating the UK's Official Secrets Act by gathering information "that could be useful to an enemy" and planting fake bombs at a military base.
He was discharged from the UK army after his arrest earlier this year and denied the allegations.
His trial is set for November.
The breakout ignited a storm of criticism as political opponents linked the escape to years of financial austerity by the UK's governing Conservative Party.
The government said an independent investigation would determine how Khalife escaped the medium-security prison that opened in 1851 during the reign of Queen Victoria.
"We need answers about how on earth a prisoner charged with terror & national security offences could have escaped in this way," Yvette Cooper, a member of the Labour Party in the House of Commons, wrote on social media on Saturday.
Prime Minister Rishi Sunak thanked the police and public and said the inquiry would get to the bottom of how Khalife got away.
The escape prompted extra security checks at major transport hubs, particularly in and around the Port of Dover, the main boat crossing from England to France, and led to the shutdown of a major highway at one point.
London counter-terror police had offered a 20,000 pound ($A39,000) reward for information leading to his arrest.
It was not immediately clear if anyone was in line for the reward.
Police on Friday had announced a breakthrough in the search after a witness reported seeing Khalife at a busy intersection near the prison shortly after the escape.
Metropolitan Police's counterterrorism commander Dominic Murphy would not say if the sighting was confirmed by surveillance cameras but London has one of the most robust security camera networks in the world and any footage could have helped track his whereabouts.
"In terms of the investigation, it really gathered momentum yesterday afternoon, with a number of calls from the public but really took a different course last night when we did an intelligence-led search in the Richmond area in the early hours of this morning," Murphy said.
"Whilst we didn't find him at that search, while we were at that search, we had a number of calls from the public over the next hour or two, giving us various sightings of him."
Police had received reports he was seen in the Chiswick area of west London and they descended there on Saturday morning, with police cars and vans swarming the area and helicopters hovering overhead.
Paul Wade said he opened his curtains to find five police officers outside his home.
"They said 'I expect you know why we are here'," he said.
"They were checking everybody's gardens."
But Khalife was nowhere near there when a plainclothes officer ultimately made the collar in the late morning, Murphy said.
Khalife was pulled off a bicycle along the canal near the community of Northolt, about 16km from where he escaped.
Murphy said he was co-operative when arrested.
He faces additional charges of being unlawfully at-large and being an escaped prisoner.