Iran's judiciary will soon make public the findings of a probe into the death in detention of a blogger whose fate provoked an international outcry, its High Council of Human Rights said.
"All aspects of the case have been accurately investigated following a special order by judiciary chief Ayatollah Sadeq Larijani," the council said in a statement reported by media on Sunday.
It said the judicial authorities would "soon" make the findings public.
Opposition activists say blogger Sattar Beheshti, 35, was tortured to death in prison for criticising Iran's regime on the Internet.
The council partially confirmed the claims, saying Beheshti "passed away while being interrogated in a police department."
It also promised "swift and decisive prosecution of anyone who purposefully or negligently was involved" in Beheshti's death.
According to opposition groups, Beheshti's family was asked on Wednesday to collect his body from the notorious Kahrizak detention centre in south of the capital.
Beheshti had been held in Kahrizak since his arrest at the end of October after criticising the government in his blog.
In his last blog entry before being detained, Beheshti had said he was being harassed by security agents who called him on the phone constantly.
"Yesterday they threatened to tell my mother that she would soon be wearing black if I did not shut up," he wrote in one post.
Earlier, the deputy of Iran's parliament said the assembly had launched a probe of its own into Beheshti's death.
"The national security commission is aware of this case and has begun an investigation," Mohammad Hassan Abutorabi was quoted by the ISNA news agency as saying.
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"I have asked the head of the commission, Aladin Borujerdi, to inform parliamentarians and the public once the investigation is completed," he said.
The wave of reactions in Iran came after the United States and France last week called on Iran to investigate the circumstances of Beheshti's death after rights group Amnesty International said he may have died under torture.
"Iranian authorities must immediately carry out an independent investigation into his death, including whether torture played a part in it," said Amnesty's Ann Harrison.
"Fears that Sattar Beheshti died as a result of torture in an Iranian detention facility, after apparently lodging a complaint about torture are very plausible, given Iran's track record when it comes to deaths in custody," she added.
Washington said it was "appalled by reports" that the blogger was "tortured and killed" in prison.
State Department spokeswoman Victoria Nuland said Beheshti was "arrested for a crime no greater than expressing his political opinion online."
A French foreign ministry spokesman said Paris was "profoundly shocked" to have learned of Beheshti's death in custody.
The statement by Iran's judiciary came after outspoken MP Ahmad Tavakoli joined in the criticism on Sunday, Mehr news agency reported.
"Why doesn't the judicial apparatus give explanations? There has been a death and it must be explained," said the conservative lawmaker, charging that Beheshti's death has fuelled what he called anti-Iran propaganda by foreign governments.
Tavakoli also criticised the regime's repression of bloggers, saying the judiciary would do better "to fight against corruption rather than making life difficult for bloggers."
Hundreds of opposition figures -- politicians, journalists, bloggers, lawyers, rights activities, union figures and media workers -- are in Iranian prison, according to international human rights groups.
The Kahrizak detention centre, where Beheshti was reportedly killed, was temporarily shut down by Iran's supreme leader Ayatollah Ali Khamenei in July 2009 after three inmates died following mistreatment by guards.