Clinton said that the US, which is embroiled in a long-running dispute with Iran over the country's nuclear programme, had asked Swiss diplomats in Tehran for the "most accurate, up-to-date information" on Saberi.

Accused of spying

Abdolsamad Khoramshahi, Saberi's lawyer, said that the journalist had been informed of the charges against her and was to appear in court next week.

Khorramshahi said he could not comment on the accusation of spying as he had not been allowed to see the legal papers.

Saberi, an American citizen whose father is Iranian, has lived in Iran for the past six years and has reported from Tehran for the BBC and for America's National Public Radio.

Iranian officials said at the time of her arrest that the US-born journalist was working in Iran with expired press credentials.

Hassan Haddad, Iran's deputy prosecutor for security issues, said that Saberi had confessed to taking part in espionage activities, Iran's English-language Press TV said.

"She has been charged and a branch of the Revolutionary Court is reviewing her case now," Isna, the Iranian news agency quoted him as saying, referring to the Iranian court that deals with security issues.

The judge in the case told Iranian state television: "Journalism for this accused ... was a cover to collect information and intelligence and transfer them to America's intelligence service."

The television gave only the judge's last name, Heydarifard.

'In good spirits'

On Monday, Saberi's parents, Reza and Akiko, who both live in the US, were allowed to visit their daughter for about 30 minutes at the prison in Evin - their first visit since she was detained.

The two said that "Roxana was in good health and in good spirits", Khoramshahi told the Associated Press news agency.

They have appealed to Ayatollah Ali Khamenei, Iran's supreme leader, for their daughter's release.

Last week Clinton said that the US had given a letter to Iranian officials during a meeting in Europe, seeking Iran's help in resolving the cases of Saberi and of two other Americans detained in Iran.

Tehran denies receiving any such letter.

Saberi's case is likely to be dealt with by a "revolutionary court", which usually presides over matters involving state security.

Under Iran's penal code, the crime of spying can carry the death penalty.