Mr Mokhtari - an outspoken critic of press censorship in Iran - had been missing since last Thursday.

His relatives maintain that the police discovered his body a day later, but the family was not informed until Wednesday.

His son eventually found his body after paying a return visit to a Tehran mortuary. The cause of his death is not yet known.

Demands for freedom

President Khatami: Under pressure from conservative faction

Mr Mokhtari had recently been involved in attempts to revive Iran's professional association of writers. He was strong opponent of censorship and was one of more than a hundred writers who signed an open letter to the Iranian authorities four years ago demanding freedom of expression and association.

He is the second dissident Iranian writer to have died in mysterious circumstances in recent weeks. His death follows the killing of two prominent Iranian opposition leaders, Darioush and Parvaneh Foruhar, last month.

Power struggle

These incidents come amid a continuing power struggle between the moderate President, Mohammad Khatami, and Iran's powerful conservative faction.

BBC regional analyst Pam O'Toole says his death will fuel allegations that hardline elements within Iran are launching a new wave of terror against prominent dissidents, in an attempt to discredit Mr Khatami.

The President - elected on a pledge to impose the rule of law in Iran - is under growing pressure to halt the violence.