The parents of an American journalist convicted of spying in Iran and sentenced to eight years in prison said their daughter is in good condition.

"She seems to be OK," Roxana Saberi’s Iranian-born father told The Associated Press after he and his wife visited their daughter in Evin prison north of Tehran.

He said his daughter was looking forward to the appeals process because she believed the verdict was too harsh for her.

Saberi’s mother, Akiko, denied her daughter was spying, adding that "once you know her she is the last person to do that."

The prison visit comes as Iran's judiciary chief ordered a full investigation into Saberi's case.

Iranian President Mahmoud Ahmadinejad has also asked the chief Tehran prosecutor to ensure Saberi is allowed to offer a full defence in the appeal.

U.S. Secretary of State Hillary Clinton called Monday for Iran to release Saberi and said she hoped for positive action from the judiciary chief's order.

"We believe she should be freed immediately, that the charges against her are baseless and that she has been subjected to a process that has been non-transparent, unpredictable [and] arbitrary," Clinton told reporters.

On Sunday, U.S. President Barack Obama said he was "gravely concerned" about Saberi's safety and well-being and was confident she was not involved in espionage.

But Iran's Foreign Ministry appeared to take a swipe at Obama — who studied law and taught constitutional law — saying "those who studied law" should not comment on the case without seeing the context.

Saberi, who is a citizen of both the United States and Iran, was arrested in late January and taken to Tehran's Evin prison.

She was initially accused of working without press credentials, but earlier this month a judge in Tehran levelled a far more serious allegation, charging her with spying for the U.S.

Saberi is of Iranian and Japanese descent and moved to Iran six years ago from Fargo, N.D., where she grew up, according to a website set up to campaign for her release.

She has worked for both the U.S. public network National Public Radio and the British Broadcasting Corporation, but Iranian officials said her press card became invalid three years ago.

With files from the Associated Press