TEHRAN, Iran (CNN) -- A U.S. journalist jailed in Iran for espionage is on a hunger strike, and plans to keep it up until she is freed, her father told CNN on Saturday.
Roxana Saberi, 31, was sentenced last week to eight years in prison after a one-day trial that was closed to the public. Her father, Reza Saberi, confirmed the hunger strike, saying she started it on Tuesday.
"She was supposed to see her lawyer on Thursday but the lawyer could not get permission from the courts to go see her," Reza Saberi said. "She says she will continue the strike until she is free from prison."
Reza Saberi said he spoke to his daughter in a one-minute call, and "she did not give us the chance to tell her not to do it."
President Obama and other U.S. and international officials have denounced the Iranian court's actions.
Saberi's legal team has said it will appeal her conviction. Judiciary Chief Ayatollah Hashemi Shahroudi has ordered the head of Iran's Justice Department to make sure the appeals process is quick and fair, according to Iranian state media.
Iranian officials initially said Saberi was held for buying a bottle of wine. The Foreign Ministry later said she was detained for reporting without proper credentials.
Saberi, who is from North Dakota, has been living in Iran since 2003, said the Committee to Protect Journalists, a journalists' advocacy group.
She has freelanced for National Public Radio and other news organizations, and was writing a book about Iranian culture.
Iranian authorities revoked her press credentials in 2006, but Saberi continued to file short news items without permission, the journalists' group said.
Saberi was detained in January, although no formal charges were disclosed. On April 9, word emerged that Saberi had been charged with espionage.
"Without press credentials and under the name of being a reporter, she was carrying out espionage activities," Hassan Haddad, a deputy public prosecutor, told the Iranian Students News Agency.
Authorities also said Saberi had confessed. Her father said he thinks she was coerced into making damaging statements.
Shirin Ebadi, an Iranian human-rights activist, has joined Saberi's legal team. Ebadi won a Nobel Peace Prize in 2003.