The Iranian Foreign Ministry summoned on Tuesday the Swiss envoy in Tehran over the United States’ detention of an American-born anchorwoman.

The Tuesday report by the official IRNA news agency quotes Bahram Ghasemi, ministry spokesman, as saying Tehran lodged a "strong protest" over the detention of Marzieh Hashemi in a meeting with the Swiss ambassador.

Ghasemi said Tehran also demanded Hashemi's "unconditional" release.

The Embassy of Switzerland looks after Washington's interests in Tehran.

US-born Hashemi, who works for Iran's English-language Press TV, was arrested on arrival at St Louis Lambert International Airport on January 13, according to family and friends cited by Press TV.

Hashemi, a Muslim convert who changed her name from Melanie Franklin, had reportedly been visiting her ill brother and other family members.

A US court on Friday confirmed the arrest, saying her testimony was required over an unspecified case but that she was not accused of a crime.

At a hearing in Washington, a judge ordered the partial unsealing of an order on Hashemi.

The court said Hashemi was arrested on "a material arrest warrant" and would be let go after she gave testimony to a grand jury investigating unspecified "violations of US criminal law".

Iran's Foreign Minister Mohammed Javad Zarif on Thursday described the detention as a "political action" by the United States that "tramples on freedom of speech" and demanded she be set free.

Zarif said that since Hashemi was married to an Iranian she is considered as an Iranian national and "it is our duty to defend our citizens".