An Iranian graduate student at the University of Texas went on trial Tuesday in Tehran on charges of having relations with a hostile country and receiving illegitimate funds, his lawyer said.
Omid Kokabee pleaded not guilty to both charges during the trial's opening session, said the attorney, Saeed Khalili. He could face up to 10 years in prison if convicted.
Iranian authorities arrested the 29-year-old Kokabee in February at Tehran's international airport as he was about to get on a flight to return to the U.S. after a short vacation in Iran.
Kokabee was studying optics in the physics department of the University of Texas and had previously specialized in lasers, one of his academic advisers said. None of his studies were linked to nuclear applications, said John Keto, chair of the graduate studies program at the University of Texas at Austin's department of physics.
Iran's nuclear program is a major source of tension between Tehran and Washington. The U.S. and other countries accuse Iran of making all the necessary preparations to build a nuclear arsenal. Iran denies that and says its nuclear work has only peaceful aims, like power generation.
The student's lawyer told The Associated Press that he was not been permitted to speak with Kokabee at Tuesday's trial session.
"He denied all charges. The entire session was allocated to (procedural) hearings and the court is to hold another session," Khalili said. No date was set for the next hearing.
There were few details on the precise accusations against the student.
Many Iranian students apply to study in the U.S. every year, but the acrimonious relations between the two countries means that any contact between an Iranian and the United States can raise suspicions in Tehran.
The two countries have never restored diplomatic relations severed in the wake of Iran's 1979 revolution, and in recent years Tehran has repeatedly accused the U.S. of fomenting unrest inside Iran.
Keto said Kokabee had difficulty getting a visa to the United States.
"It took a number of letters to the State Department. But he finally arrived here in August of 2010 and started graduate school," Keto said.
Since 2007, a number of U.S.-Iranian dual nationals or Americans of Iranian ancestry have faced arrest, imprisonment or criminal charges when visiting Iran.
Iran last month released two Americans who had been convicted of illegal entry and espionage after they were arrested along the border with Iraq in July 2009.
Keto said that the university first learned of Kokabee's arrest from another student after he failed to show up for his studies.
"His family actually asked us at that time not to make a big deal out of this because they felt like some kind of rabble rousing from the U.S. would not be in his interest," he said.
Associated Press writer Chris Tomlinson in Austin, Texas, contributed to this report.