A British-Iranian woman jailed in Iran after trying to watch a volleyball match is on a hunger strike for the second time, reports say.

Ghoncheh Ghavami was sentenced to a year in jail after attempting to attend a men's volleyball match between Iran and Italy in Tehran in June, her lawyer told Iranian media.

The  25-year-old law graduate from London, is protesting against what she called her "illegal detention", her mother told the BBC.

Woman are banned from attending volleyball and football matches in Iran, which officials say protects them from lewd behaviour.

She was arrested on June 20 outside Tehran's Azadi Stadium, where she was taking part in a demonstration demanding that women be allowed inside to watch the international league match.

Ghavami was released soon after, but then re-arrested days later when she was called back to reclaim items that had been confiscated when she was first detained.

The status of Ghavami's case is uncertain because prosecutors have not confirmed her sentence, according to the broadcaster.

Ghavami previously went on a hunger strike for two weeks before her sentencing, when she was detained for months before going on trial behind closed doors.

The human rights group Amnesty International says she has been held at Evin prison, which has a reputation for brutality, and has spent time in solitary confinement.

Iran does not recognise dual citizenship and treats dual nationals as Iranians.

Despite an international outcry against the case, last month, a 26-year-old Iranian woman was executed in Tehran for killing a man who she said had tried to sexually abuse her.

Source: Agencies