A panel of Russian judges has ordered the early release of an American student who was serving time on drug charges, in a case that had strained U.S. - Russian relations.

American scholar John Tobin walked out of a Russian prison in the southern city of Rosshosh on Friday, after a court approved his early parole. He was accompanied by officials from the American embassy and did not talk to reporters. Mr. Tobin was serving a one year sentence on drug charges.

The 24-year-old student was arrested earlier this year in the southern city of Voronezh and charged with marijuana possession. He was studying political science at the Voronezh State University on a Fulbright scholarship.

But the case gained international notoriety a month later when local officials from the Federal Security Service, the FSB, accused him of being a spy in training. They said he came to Russia to familiarize himself with the language and culture before starting work for American intelligence.

However, they never charged him with espionage. Mr. Tobin said the drugs were planted on him because he rejected an offer by the FSB to work for the Russian intelligence agency.

His arrest raised suspicions because it came at a time when the U.S. and Russia were locked in a spying dispute, each accusing the other of spying. Mr. Tobin's defense team said they believed he had been caught up in that dispute.

John Tobin became eligible for parole on Thursday after serving half of his one year sentence. It is not clear yet whether he will be sent immediately back to the U.S. or whether he will have to stay in Russia as part of his parole.