Chinese state media say a former computer technician has been sentenced to death for selling 150,000 classified documents to an unidentified foreign spy agency.

State broadcaster CCTV on Tuesday said Huang Yu, who once worked for a Chinese research firm specializing in encryption, received $700,000 for providing the documents between 2002 and 2011.

CCTV did not say when Huang was tried on the espionage charge. The case was publicized as part of a national campaign to raise public awareness about state security following China's first national security education day last Friday.

Huang was shown with his head shaved and dressed in prison garb discussing his case on television. He urged others aiding foreign countries in spying against China to turn themselves in.