AFP - An elderly US couple charged with spying for Cuba for almost 30 years pleaded guilty in the conspiracy Friday, with the husband agreeing to serve a life sentence, the US Justice Department said.

Former State Department official Walter Myers, 72, pleaded guilty to one count of conspiracy to commit espionage and two counts of wire fraud, while his wife Gwendolyn Myers, 71, pleaded guilty to conspiracy to gather and transmit national defense information, according to the department.

Gwendolyn Myers will serve between six and 7.5 years behind bars, while the pair agreed to forfeit some 1.7 million dollars, the amount of a monetary judgment against them.

"For the past 30 years, this couple betrayed America's trust by covertly providing classified national defense information to the Cuban government. Today, they are being held accountable for their actions," David Kris, assistant attorney general for national security, said in a statement.

"These guilty pleas should serve notice that we remain vigilant in protecting our nation's secrets and in bringing to justice those who compromise them."

The Myers were arrested on June 4 after an undercover FBI sting operation having allegedly passed on secrets for decades to Washington's Cold War foe via shortwave radio and in shopping carts.