TEHERAN (AFP) - An Iranian court has rejected accusations of premeditated murder against a policeman over the death in custody of an opposition blogger, the reformist Sharq daily reported on Wednesday.

Sattar Beheshti, 35, died at the notorious Kahrizak prison a few days after he was arrested in October 2012 following criticism of the government in his blog, according to opposition groups who allege he was tortured to death.

An unnamed officer from a police cybercrime unit still faces manslaughter charges over Beheshti's death, after the criminal court rejected the complaint of premeditated murder lodged by a lawyer representing the blogger.

Preliminary investigations by the coroner, the prosecutor and the parliamentary committee suggest Beheshti's death was caused by mistreatment, either through beating or psychological torture, at the hands of the police.

"The criminal court... said the case of murder was closed because the court rejected the charge of premeditated murder," said Giti Pourfazl, a lawyer acting for Beheshti's family.

Pourfazl said the court had suggested she "lodge another complaint for manslaughter".

"I haven't agreed to lodge a complaint, and I have to consult my client in this regard," said Pourfazl, adding that "we still consider Beheshti's death was premeditated murder".

Premeditated murder is among the crimes punishable by death in Iran, based on its interpretation of sharia law in force since its 1979 Islamic revolution.

A number of probes were launched after UN experts and some Western states condemned Beheshti's death and demanded Teheran investigate it, with Amnesty International saying he may have died from torture.

Alaeddine Boroujerdi, who heads parliament's national security and foreign affairs committee, took issue with claims by pathologists that Beheshti had died from shock and fear, saying he had "very clearly" been beaten while in detention.

He called on the police unit involved to "seriously review its practices".

The death also led to the dismissal of the head of Iran's police cybercrime unit, launched in January 2011 to confront anti-regime conduct on the Internet.

Hundreds of opposition figures - politicians, journalists, bloggers, lawyers, rights activities, union figures and media workers - are in Iranian prisons, according to international human rights groups.