A Russian court on Tuesday ordered the release on parole of physicist Valentin Danilov, who was convicted of spying for China in 2004 and sentenced to 14 years in a prison colony, an official said.

"Unless one of the sides appeals this decision, Mr. Danilov will be freed in 10 days, when the decision goes into effect," the spokeswoman for Krasnoyarsk regional court Natalia Mishanina, told AFP.

Danilov, a former director of the thermo-physics centre at Krasnoyarsk State University was charged with selling state secrets to a Chinese organisation by the FSB security service, jailed in 2001 and eventually convicted in 2004.

The 64-year-old is currently serving his 14-year-term in a high-security prison in the Siberian city of Krasnoyarsk and will remain there until his release, a spokeswoman for the regional prisons service told Russian news agencies.

Danilov served out the majority of his sentence, with only three years and around two months remaining, Mishanina said. The decision to free him was made after he appealed for parole.

The controversial conviction had been made after a drawn-out high-profile trial, in which the Supreme Court eventually overturned an acquittal granted by a jury in 2003.

Danilov repeatedly pleaded his innocence, claiming that the information he passed to China was already in the public domain. Russia's scientific community, including notable Nobel laureates, appealed for his freedom.

His case brought attention to the FSB security service's growing strength under President Vladimir Putin, who was one year into his first term in the Kremlin when Danilov was arrested in 2001.