Police are searching the Chiswick area in west London as the hunt for terror suspect Daniel Khalife enters its fourth day.

Officers are focusing on the district after “intelligence-led activity” and confirmed sightings in the area overnight, including calls from members of the public, the Metropolitan Police said.

They will be carrying out “intensive” searches throughout the day.

Officers have been stopping and checking cars, inspecting car boots and asking residents for their IDs.

Armed officers and police dogs are in the area while a police boat can be seen on the River Thames close to the roads.

The 21-year-old is believed to be wearing a black baseball cap, black T-shirt and dark-coloured bottoms, and carrying a small bag or case, the force said.

It added: “We urge members of the public in that area to remain vigilant and call 999 immediately should they see Khalife, or if they have any information that could assist the search.

“Whilst we advise members of the public not to approach Khalife if they see him, we still assess that he does not pose a threat to the wider public.”

It comes as Khalife’s family urged him to “give himself up”.

The former soldier is believed to have escaped from HMP Wandsworth on Wednesday morning by strapping himself to the bottom of a delivery lorry after leaving the prison kitchen in a cook’s uniform.

The force is offering a £20,000 reward for anyone with information that leads to the arrest of the former soldier, who was awaiting trial after allegedly planting a fake bomb at an RAF base and gathering information that might be useful to terrorists or enemies of the UK.

He was discharged from the Army in May.

Speaking to The Times, a close relative of Khalife said he was a “very, very intelligent, easygoing and kind boy” who had changed in recent years – even going missing in the weeks before he was charged.

They told the paper: “If I could talk to him, I would tell him to end this and give himself up, even though I understand he is afraid.

“Two years ago he was quite happy; he said he never wanted to leave, he said they were good people, and then something happened last year.

“He was scared to talk about it and so he ran away. I don’t believe the allegations, he spent four years in the Army.

“It is just silly to imagine he would betray them.”

Video footage obtained by the PA news agency shows police officers searching a Bidfood lorry with a sniffer dog after it was stopped as witnesses told of their shock as they learned about the incident.

Speaking on LBC on Friday, Met Commissioner Sir Mark Rowley said Khalife’s escape was “clearly pre-planned” and “it is a question” whether it was an inside job.

Speaking to broadcasters in New Delhi, Prime Minister Rishi Sunak would not comment on suggestions there could be foreign state involvement in the escape.

The relative said Khalife had only visited Iran twice when he was young, telling The Times: “Danny doesn’t know Iran, he loves this country.”

Khalife’s disappearance has prompted questions over staffing levels at the Victorian jail and whether he should have been in a higher security prison.

Strapping was found underneath the delivery lorry which police stopped just over an hour after it left the prison at 7.32am, with officers suggesting Khalife held on to the bottom of the vehicle to escape.

Khalife was declared missing at 7.50am, with police notified at 8.15am. The lorry was stopped on Upper Richmond Road, near the junction of Carlton Drive, at 8.37am.

CCTV footage later emerged of the van driving along a road in London after it had left the prison.

Justice Secretary Alex Chalk confirmed an independent investigation will take place after Khalife’s escape, alongside two urgent reviews looking at the categorisation and placement of all HMP Wandsworth prisoners and all those in custody charged with terrorism offences.

The former soldier, who denied the three charges against him, is described as slim, 6ft 2in, with short brown hair.

Khalife has links to the West Midlands – having been stationed at the Ministry of Defence’s Beacon Barracks in Stafford – and Kingston upon Thames in south-west London, but Mr Murphy said the hunt is covering the whole of the UK.

Kent Police said on Friday evening that junctions eight and nine of the M20 had reopened after being temporarily shut on Thursday due to the enhanced security checks involved with the search for Khalife.