Iranian security forces have prevented devotees of fans of late poet Ahmad Shamlou, who pushed for greater freedoms and had some of his work banned under successive governments, from marking the 18th anniversary of his death.

Eyewitnesses told RFE/RL’s Radio Farda that dozens of supporters of Shamlou attempted to hold a commemoration ceremony by his grave at a cemetery in the city or Karaj, west of Tehran, on July 24.

But security forces shut the gates of the cemetery in order to prevent any gathering at Shamlou's grave, a member of Iran's Writers Association who attempted to attend the event said.

Shamlou, who wrote poems describing an atmosphere of fear and repression following the 1979 revolution that brought the shah down and led to Islamic rule, is considered by many to have been Iran's most influential contemporary poet.

Some of his work was banned in Iran under the secular rule of the Western-backed shah.

Authorities have in past years repeatedly prevented people from marking Shamlou's death and remembering him at his grave in Karaj.

This year, eyewitnesses said the gates of the cemetery remained shut after security forces dispersed the crowd.

Reports said up to five people were detained, including two members of the Writers Association, which has in recent years come under pressure from authorities.

One of those detained was later released, reports said.

Shamlou was awarded the Freedom of Expression prize by Human Rights Watch (HRW) for his efforts in support of human rights.

He died in Tehran in 2000.