KNOXVILLE, Tenn. (AP) -- Two foreign graduate students say they had no knowledge of laws barring the release of sensitive information when they worked for a former University of Tennessee professor accused of passing secrets from a military research contract.

J. Reece Roth, a 71-year-old expert in plasma physics, is being tried this week in federal court in Knoxville. He faces 18 counts of conspiracy, fraud and violating the Arms Export Control Act.

Prosecutors say he gave the student lab assistants, one from China and the other from Iran, access to his work on a U.S. Air Force contract to develop a new guidance system for unmanned aircraft, or drones.

The Arms Export Control Act prohibits the exchange of sensitive information to foreign nationals.

------

(Copyright 2008 by The Associated Press. All Rights Reserved.)