Panamanian President Juan Carlos Varela said on Friday that the U.S. State Department had approved his request to extradite his predecessor, former president Ricardo Martinelli, who is jailed in Miami on spying charges.

"The foreign ministry ... has received a diplomatic letter on behalf of the State Department informing of approval of extradition," Varela told journalists at an event.

Martinelli was jailed in the United States last year after Panama requested his extradition on charges that he used public money to spy on more than 150 political rivals during his 2009-2014 term.

Martinelli has maintained his innocence and claims to be a victim of a political attack by Varela.

"The former president Martinelli was mentally prepared for whichever of the two decisions the State Department could take," Luis Eduardo Camacho, a spokesman for Martinelli, wrote in a post on Twitter. "The fight will now be in Panama."

Camacho did not immediately respond to a request for further comment.

Roniel Ortiz, a lawyer for Martinelli in Panama, did not immediately respond to a request for comment either.

A U.S. court authorized the extradition last year, and Martinelli in May said he would stop fighting the proceedings for judgment in Panama.

In a letter released in May, Martinelli said he had expected the United States to protect him in exchange for his assistance with U.S. issues, such as curbing cross-border crime.