A Royal Navy submariner has admitted collecting secret coding programmes that could be useful to an enemy of the UK.
Petty officer Edward Devenney, 30, from Northern Ireland, pleaded guilty at the Old Bailey to gathering details of encryption programmes in breach of the Official Secrets Act.
He also admitted a charge of misconduct in a public office in relation to a meeting with two people he thought were from the secret service of another state.
Devenney admitted meeting two people whom he thought were from the Russian secret service and discussing information relating to the movement of nuclear submarines.
The Official Secrets Act charge was collecting information for a purpose prejudicial to the safety or interests of the State between November 18 last year and March 7 this year.
He gathered details of "crypto material" - programmes used to encrypt secret information - which could be useful to an enemy.
Devenney denied a second count of communicating information to another person and this will not be pursued by prosecutors.
He will be sentenced on December 12 at the Old Bailey, when parts of the hearing will be held in secret.
Mr Justice Saunders told him: "Your sentence will be adjourned to December 12 when I will hear all the matters and consider them all.
"Until then you are remanded in custody."