Daniel Khalife, 23, was found guilty in November of espionage and terrorism charges as well as for escaping prison.

A judge at Woolwich Crown Court in southeast London sentenced him to 14 years and three months jail for embarking on a "dangerous and fantastical plan" that involved passing sensitive information to Iranian intelligence for cash.

Khalife, whose mother is Iranian, gathered information, including the names of elite special forces personnel, over a two-and-a-half-year period while posted in the UK and United States before being arrested and charged in 2023.

"The mere fact that you started on this dangerous and fantastical plan demonstrates your immaturity and lack of wisdom," said Justice Bobbie Cheema-Grubb.

Prosecutors accused Khalife of playing a "cynical game", making contact with a man linked to Iranian intelligence after joining the British army.

He subsequently told British intelligence he wanted to be a double agent, in what his defence lawyer termed a "hapless" ploy.

In September 2023, Khalife escaped a London prison strapped to the underside of a food delivery truck, sparking a three-day nationwide manhunt and raising concerns about prison security.

"This sentence reflects the gravity of the offences committed by Khalife," said Dominic Murphy, head of the Metropolitan Police's Counter Terrorism Command.

"The threat to the UK from states such as Iran is very serious, so for a soldier in the Army to be sharing sensitive military material and information with them is extremely reckless and dangerous," Murphy added in a statement.

Khalife, who grew up in southwest London, joined the army in 2018 aged 16.

Cheema-Grubb said she had "no doubt" that Khalife used his Iranian heritage to gain the trust of his contacts.

During the trial, jurors were shown a photograph from Khalife's phone of a handwritten list he had made of 15 soldiers, including their service number, rank, initials, surname and unit.

The details of special forces personnel was "undoubtedly valuable, and giving them to an enemy state would have very substantially increased the risk to them and to their operational effectiveness," the judge said.

Khalife allegedly remained in contact with Iranian handlers while posted to Fort Hood, Texas, between February and April 2021, where he was given the second-highest level of NATO security clearance, one below "cosmic top secret".

He also travelled to Turkey to meet his Iranian handlers, and twice collected money in exchange for information.