A British navy sailor was jailed for eight years Wednesday for trying to pass nuclear submarine secrets to men he thought were Russian spies.

Edward Devenney, 30, "was prepared to betray his country and his colleagues", Judge John Saunders said at the Old Bailey Central Criminal Court in London as he sentenced the petty officer.

The court heard that Devenney rang the Russian embassy in November last year, after being passed over for promotion.

In January he met people he believed were Russian agents but were in fact British intelligence officers.

Devenney "did supply details of movements and operations carried out and to be carried out by nuclear submarines," said Saunders.

"I am satisfied that in the wrong hands it was capable of affecting the operational effectiveness of nuclear submarines."

Devenney pleaded guilty to breaching the Official Secrets Act by gathering classified information and to misconduct by meeting the supposed spies.