"My colleagues and I are certain that the accusations against Oleg Korobeinichev are unfounded," Sergei Dzyuba said. "The scientist has been involved in purely scientific research, which does not have practical applications."

Korobeinichev, 65, was awarded a research grant in 2002 under the U.S. Department of Defense scientific program to study the fundamental combustion processes in rocket fuels, which is a common practice at the Novosibirsk-based institute, Dzyba said.

"The work under this grant is being conducted for four years, with an annual budget of $45,000, but we had to suspend reporting the progress [to the American side] because of the ongoing investigation," he said.

Korobeinichev, who has not been formally charged but has been ordered not to leave the country, refused to admit any guilt and continues research work at the institute.

There have been several spy cases in Russia against scientists in the past three years that have been widely covered by the Russian media. Physicist Valentin Danilov was sentenced to 14 years in prison for high treason in November 2004 for allegedly passing sensitive information to China. In the summer of 2005, his term was reduced to 13 years.

In April 2004, Igor Sutyagin, head of the military technology and economics department at the Institute of the United States and Canada, was sentenced to 15 years of prison for sharing state secrets with U.S. military intelligence.

In February 2006, a Moscow court ordered that Igor Reshetin, a member of the Russian Academy of Cosmonautics, remain in custody after he was charged with sharing data on dual-purpose technologies with a Chinese corporation.

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