TEHERAN - The United States has released Iranian TV journalist Marzieh Hashemi after detaining her for 10 days.

The US-born Louisiana native had been arrested on a material witness warrant and was subsequently released after testifying in front of a grand jury. It was not clear what the grand jury is investigating.

Iran's Foreign Ministry had called her Jan 13 arrest by the FBI "illegal".

Hashemi, who holds dual citizenship, has been living in Iran for years and was detained by the FBI at the airport in St. Louis, Missouri, while making a family visit. She had not been accused of any crime.

On Tuesday, the Iranian Foreign Ministry handed an official note to the Swiss ambassador in protest of the US detention and "inhumane and discriminatory" behavior toward the Press TV journalist. Iran asked for her "immediate and unconditional" release.

Diplomatic relations between Iran and the US were severed in 1979, after which the US appointed Switzerland to protect its interests in Iran.

Xinhua