The father of an American journalist charged by Iran with espionage called on Iran Thursday to free her and said in an exclusive interview with Associated Press Television News that he will not leave the country until she's released. "I demand them to release my daughter as soon as possible so that she can return to her normal life and continue her job," Reza Saberi said. "I will stay here until she is freed." Roxana Saberi has been living for the last six years in Iran, working as a reporter for such organizations as National Public Radio and the British Broadcasting Corp. The 31-year-old freelance reporter was arrested in late January. A judge announced Wednesday that she had been charged with spying for the United States, a far more serious development than earlier statements by Iranian officials that she had been arrested for working without press credentials - and her own assertion in a phone call to her father that she was arrested after buying a bottle of wine. The judge told Iranian state TV that Saberi was passing classified information to US intelligence services. "Under the cover of a journalist, she visited government buildings, established contacts with some of the employees, gathered classified information and sent it to the US intelligence services," said the judge, who under security rules was identified only by his surname, Heidarifard. "Her activities were discovered by the counterespionage department of the Intelligence Ministry," Heidarifard said. Reza Saberi and his wife arrived in Iran Sunday and visited their daughter Monday in Evin prison, which often holds political prisoners, north of Teheran. "We were allowed to visit her for about 20 minutes. We talked to her. She was spiritually better than before. However, she was physically extremely thin and weak but she said she eats now and is going to exercise. This gave us the hope that she will become better," Reza Saberi said. Saberi will stand trial next week, the judge said, though he did not specify which day. The journalist grew up in Fargo, North Dakota. The Iranian judge in the case told state TV that Saberi's American nationality had not yet been ascertained for the Iranian judiciary, but her father said she was definitely an American citizen. "She is certainly an American national. She also came to Iran and received an Iranian ID card and passport and according to Iranian law, she is Iranian too. She is actually a dual citizen," her father said. Saberi's father, under advisement from the lawyer representing his daughter, would not comment on whether he accepted the charges or not. The journalist's arrest comes at a time when President Barack Obama has expressed a willingness to talk with Iran after many years of rocky relations under the former US administration. On Wednesday, administration officials said US diplomats would attend group talks with Iran over its suspect nuclear program. That would be a major departure from President George W. Bush's policy of isolation from a nation it once deemed to be evil. The US has also been pushing for Saberi's release, and US Secretary of State Hillary Rodham Clinton said Wednesday the US was deeply concerned by the reported charges and was seeking information from Swiss diplomats in Teheran. The US broke off diplomatic relations with Iran following the 1979 Islamic revolution and the hostage-taking at the US embassy in Teheran. Saberi was one of three missing or detained Americans mentioned in a written message passed by American officials directly to Iranian diplomats last month at an international conference on Afghanistan in The Hague, Netherlands, that Clinton attended. Iran has yet to respond to the message, which sought information about the three. Human rights groups have repeatedly criticized Iran for arresting journalists and suppressing freedom of speech. The government has arrested several Iranian-Americans in the past few years, citing alleged attempts to overthrow its Islamic government through what it calls a "soft revolution." In another indication of the seriousness of the case, Saberi's lawyer also learned this week that it would be reviewed by Iran's Revolutionary Court, which normally handles cases involving threats to national security. Saberi's lawyer, Abolsamad Khorramshahi, said Thursday that he had not yet been allowed to read the text of the indictment, which he expects to see by Saturday.