Tehran - An Iranian-American reporter detained in Tehran for illegal press activities has bee charged with espionage, a media report said Wednesday.

Roxana Saberi, the 31-year-old reporter working for US-based National Public Radio, was initially detained for buying alcohol and is under Iranian custody since the end of January in Tehran's Evin prison.

But Foreign Ministry spokesman Hassan Ghashghavi said in early March that Saberi was denied official press accreditation since 2006, and was working illegally.

"Without having press credentials, she was carrying out spying activities under the title of a journalist," Tehran's deputy prosecutor Hassan Haddad was quoted as saying by Student's News Agency ISNA.

Haddad said her case was sent to the revolutionary court, and claimed that "she has accepted all charges."

The release of Saberi and an inquiry about the long-missing US citizen Robert Levinson, a former agent with the US Federal Bureau of Investigation, were the subjects of a letter given to the Iranians by the US Secretary of State Hillary Rodham Clinton, during an international conference on Afghanistan late last month in The Hague.

"The secretary in her letter ... to the Iranians made very clear that we were concerned about (the Saberi) case and wanted to see it resolved," US State Department deputy spokesman Robert Wood said.

"We continue to work to try to get her released," he said. (dpa)