An Iranian court will hear Iranian-American journalist Roxana Saberi's appeal against her eight-year prison sentence for espionage on Sunday, her lawyer said on Saturday.

The 32-year-old freelance reporter was detained three months ago, and sentenced on April 18 on charges of spying for the United States, Iran's arch enemy.

The media watchdog Reporters Without Borders has said her conviction was a warning to foreign journalists working in Iran ahead of its presidential election in June.

The case could complicate Washington's efforts at reconciliation with the Islamic Republic after three decades of mutual mistrust.

The judiciary said on Tuesday the higher court would meet in a session closed to the public, but did not announce a date.

Saberi's lawyer Abdolsamad Khorramshahi told Reuters the hearing would be on Sunday. "The verdict could come next week or any other time. It is not clear when," he said.

Khorramshahi has expressed optimism that Saberi will be acquitted or have her sentence reduced, after president Mahmoud Ahmadinejad publicly called on the judiciary to ensure she was granted her full legal rights.

Saberi's father Reza, 68, said he did not know whether he would be allowed to attend the proceedings.

He moved to the United States in the early 1970s but has returned to Tehran with his wife to follow their daughter's case. "We hope our daughter will be released ... we are hopeful," he told Reuters.

On Wednesday, he said his daughter had ended a two-week hunger strike in Tehran's Evin prison, saying she was "very weak". The judiciary has denied that she refused food and said she was in good health.

Saberi, US-born but a citizen of both the United States and Iran, was arrested in January for working in Iran after her press credentials expired in 2006, and was charged with espionage later.

She has reported for the British Broadcasting Corporation and US National Public Radio.

The United States says the charges are baseless and has demanded her release. The two countries are locked in a dispute over nuclear work that the West fears is aimed at making weapons, an allegation that Iran denies.

Reporters without Borders last month said seven journalists were currently imprisoned in Iran, which it ranks 166th out of 173 countries in its press freedom index.

Iran denies that it seeks to stifle dissent. The government says it welcomes constructive criticism and upholds the principle of free speech.-Reuters