Riot police deploy in Iranian cities as people gather for Mahsa Amini's memorial

Iranian riot police deployed in large numbers in Mahsa Amini's home town of Saqez on Wednesday, witnesses said, after activists called for protests across the country to mark 40 days since she died in detention over her "inappropriate attire".

Witnesses in the capital Tehran and the cities of Tabriz and Rasht to the north also reported a heavy presence of security forces in the streets.

Protests ignited by the 22-year-old's death while in the custody of Iran's morality police on Sept. 16 have become one of the boldest challenges to the Islamic Republic's clerical leadership since the 1979 revolution.

A wide range of Iranians have come out onto the streets, with some calling for the downfall of the Islamic Republic and chanting "Death to (Supreme Leader Ayatollah Ali) Khamenei".

A witness in Saqez said the cemetery where Amini is buried was filled with members of the volunteer Basij militia and police.

"They tried to stop us from entering the cemetery... but I managed to get in. I have not seen Mahsa's parents yet," the witness said.

Another witness said residents were heading for the scene. "People have defied warnings by security forces and are going to the cemetery but there are dozens and dozens of riot police and Basij (volunteer militia) members," the witness said.

Fearing the 40-day anniversary of Amini's death would fuel further violent protests, security police had warned her family not to hold a memorial procession, rights groups said.

Authorities closed all schools and universities in the Kurdistan province on Wednesday "because of a wave of influenza", Iranian state media reported.

While students have played a pivotal role in the protests, with dozens of universities on strike, unconfirmed reports on social media showed workers at a Tehran refinery had joined in. A refinery official denied the reports.

Videos circulating on social media showed people at Saqez cemetery chanting "Death to Khamenei". Others showed security forces blocking roads leading to the town. Reuters could not verify the authenticity of the videos.

Some of the deadliest unrest has been in areas home to ethnic minorities with long-standing grievances against the state, including Kurds in the northwest and Baluchis in the southeast.

Rights groups said at least 250 protesters have been killed, including teenage girls, and thousands have been arrested.

The authorities, who have accused the US and other Western countries of fomenting what they call "riots", have yet to announce a death toll but state media have said around 30 members of the security forces have been killed.