IRNA - Pen American Center, a non-profit organization working to defend free expression in the US and the world, in a statement called for immediate release of Iran's Press TV anchor Marzieh Hashemi who had been detained by FBI on undisclosed charges.

In its recent statement, Pen America urged the US to make it clear if there are other grounds for Hashemi's detention.

Meanwhile, Pen America said in a Twitter message, 'It remains unclear why Marzieh Hashemi was detained, as she still faces no charges and is being brought as a material witness in another case. We hope to learn more about the circumstances and rationale for her detention by the US government.'

In the meantime, the International Federation of Journalists (IFJ) in a recent tweet urged American authorities to clarify the situation

The US-born Marzieh Hashemi (Melanie Franklin) who traveled to the US to visit her sick brother was arrested at St. Louis International Airport in Lambert on January 13 and transferred to a detention facility in Washington by FBI agents.

Hashemi has told her family she has been mistreated at the detention center and her hijab has been forcibly removed.

She converted to Islam after the 1979 Islamic Revolution and moved to Iran in 2008, where she started working as a TV presenter and journalist.

Earlier, the Council on American�Islamic Relations (CAIR) has urged US to be accountable to the arrest of Marzieh Hashemi, saying there is no justification for denying her religious rights.