TEHERAN (AFP) - A British-Iranian woman who was arrested in Teheran after trying to attend a volleyball match has been sentenced to one year in jail, her lawyer was reported as saying on Sunday.

Ghoncheh Ghavami, a 25-year-old law graduate from London, who was detained in June at a Teheran stadium where Iran's national volleyball team was to play Italy, went on trial last month.

"According to the verdict she was sentenced to one year," her lawyer Alizadeh Tabatabaie was quoted in Iranian media as saying, noting that the judge had shown him the sentence.

No reason was given for the conviction though Ghavami had been accused of spreading propaganda against the regime, a broad charge often used by Iran's judiciary.

Asked if the sentence could be reduced, Tabatabaie, who has not been allowed to visit his client, said: "Considering that Ghoncheh Ghavami has no criminal record, the court can alleviate the verdict.

Iranian officials have said Ghavami was detained for security reasons unrelated to the volleyball match. So far she has been held in the capital's notorious Evin Prison for 126 days.

The "Free Ghoncheh Ghavami" Facebook page where her friends and family campaigned for her release features photographs of her against the slogan: "Jailed for wanting to watch a volleyball match".

An update on the page on Sunday appeared to corroborate the one year sentence but bemoaned the closed-doors legal process that has prevailed in the case.

"This morning Ghoncheh's family and lawyer returned empty handed from branch 26 of Revolutionary court," it said.

"It is not clear to her family and lawyer as to what the current legal basis of her detention is. A fair and just legal process according to Iran's legal framework is the basic right of every Iranian citizen. Why are these rights not upheld in Ghoncheh's case?"

Ghavami's arrest came after female fans and even women journalists were told they would not be allowed to attend the volleyball match at Azadi ("Freedom" in Persian) stadium in the capital.

National police chief General Esmail Ahmadi Moghaddam said it was "not yet in the public interest" for men and women to attend such events together.

"The police are applying the law," he said at the time.

Women are also banned from attending football matches in Iran, with officials saying this is to protect them from lewd behaviour among male fans.

British Prime Minister David Cameron raised Ghavami's case during a meeting with Iran's President Hassan Rouhani in September at the UN General Assembly in New York.