An American woman working on a university exchange program was caught spying in southern Russia for the CIA, Russian intelligence officials said.

Justine Hamilton, 25, had been working in the Voronezh region with a Kansas-based exchange program since January 1998, said a spokesman for the Federal Security Service, or FSB, the main successor to the Soviet KGB.

She was summoned to regional FSB headquarters in Voronezh, located 475 kilometers south of Moscow, on June 21.

The spokesman said Hamilton admitted to gathering materials from defense factories in the region and passing on political and economic data to the CIA.

Hamilton left the country June 23, when her Russian visa expired. The FSB spokesman said that she would not be allowed back in the country. He did not say where Hamilton was from or give the name of the exchange program.