TEHRAN, Iran (AP) – An Iranian court has convicted a Flint Central High School graduate of working for the CIA and sentenced him to death, state radio reported Monday, in a case adding to the accelerating tension between the United States and Iran.

Iran charges that as a former U.S. Marine, Amir Mirzaei Hekmati received special training and served at U.S. military bases in Iraq and Afghanistan before heading to Iran for his alleged intelligence mission. The radio report did not say when the verdict was issued. Under Iranian law, he has 20 days to appeal.

The 28-year-old former military translator was born in Arizona and graduated from Flint Central. His family is of Iranian origin. His father, a professor at Mott Community College, has said his son is not a CIA spy and was visiting his grandmothers in Iran when he was arrested.

His trial took place as the U.S. announced new, tougher sanctions against Iran over a nuclear program that Washington believes Tehran is using to develop a possible atomic weapons capability.

Iran, which says it only seeks nuclear reactors for energy and research, has sharply increased its threats and military posturing against stronger pressures, including the U.S. sanctions targeting Iran's Central Bank in attempts to complicate its ability to sell oil.

U.S. State Department has demanded Hekmati's release.

The court convicted him of working with a hostile country, belonging to the CIA and trying to accuse Iran of involvement in terrorism, Monday's report said.

In its ruling, a branch of Tehran Revolutionary Court described Hekmati as a mohareb, an Islamic term that means a fighter against God, and a mofsed, or one who spreads corruption on earth. Both terms appear frequently in Iranian court rulings.

In a closed court hearing in late December, the prosecution asked for the death sentence for Hekmati.

The U.S. government has called on Iranian authorities to grant Swiss diplomats access to Hekmati in prison. The Swiss government represents U.S. interests in Iran because the two countries don't have diplomatic relations.

Hekmati is a dual U.S.-Iranian national. Iran considers him an Iranian since the country's law does not recognize dual citizenship.

Similar cases against Americans accused of spying have heightened tensions throughout years-long standoff over Iran's nuclear program.

Iran arrested three Americans in July 2009 along the border with Iraq and accused them of espionage, though the Americans said they were just hiking in the scenic and relatively peaceful Kurdish region of northern Iraq. They were eventually released and returned to the United States.An Iranian court has convicted an American man of working for the CIA and sentenced him to death, state radio reported Monday, in a case adding to the accelerating tension between the United States and Iran.

Iran charges that as a former U.S. Marine, Amir Mirzaei Hekmati received special training and served at U.S. military bases in Iraq and Afghanistan before heading to Iran for his alleged intelligence mission. The radio report did not say when the verdict was issued. Under Iranian law, he has 20 days to appeal.

The 28-year-old former military translator was born in Arizona and graduated from a high school in Michigan. His family is of Iranian origin. His father, a professor at a community college in Flint, Michigan, has said his son is not a CIA spy and was visiting his grandmothers in Iran when he was arrested.

His trial took place as the U.S. announced new, tougher sanctions against Iran over a nuclear program that Washington believes Tehran is using to develop a possible atomic weapons capability.

Iran, which says it only seeks nuclear reactors for energy and research, has sharply increased its threats and military posturing against stronger pressures, including the U.S. sanctions targeting Iran's Central Bank in attempts to complicate its ability to sell oil.

U.S. State Department has demanded Hekmati's release.

The court convicted him of working with a hostile country, belonging to the CIA and trying to accuse Iran of involvement in terrorism, Monday's report said.

In its ruling, a branch of Tehran Revolutionary Court described Hekmati as a mohareb, an Islamic term that means a fighter against God, and a mofsed, or one who spreads corruption on earth. Both terms appear frequently in Iranian court rulings.

In a closed court hearing in late December, the prosecution asked for the death sentence for Hekmati.

The U.S. government has called on Iranian authorities to grant Swiss diplomats access to Hekmati in prison. The Swiss government represents U.S. interests in Iran because the two countries don't have diplomatic relations.

Hekmati is a dual U.S.-Iranian national. Iran considers him an Iranian since the country's law does not recognize dual citizenship.

Similar cases against Americans accused of spying have heightened tensions throughout years-long standoff over Iran's nuclear program.

Iran arrested three Americans in July 2009 along the border with Iraq and accused them of espionage, though the Americans said they were just hiking in the scenic and relatively peaceful Kurdish region of northern Iraq. They were eventually released and returned to the United States.