This was Iran's first official reaction to the death of Sattar Beheshti, in a rare example of parliament taking up allegations of human rights abuses first raised internationally. The case gained publicity over the weekend when U.S. State Department and a press freedom group called for an inquiry.
It was known that the blogger died in custody, but how he died was not disclosed.
Deputy parliamentary speaker Mohammad Hasan Abutorabifard said that the legislature's influential committee on national security and foreign policy has been assigned to look into the circumstances of Beheshti's death.
"The committee has been informed about the incident and its report will be announced to the nation and lawmakers," IRNA quoted Aboutorabifard as saying.
The announcement came after a speech by lawmaker Ahmad Tavakoli, a prominent conservative critic of President Mahmoud Ahmadinejad, in the open session of the parliament that was broadcast on state radio, in which he criticized officials for their silence over a case that has received international attention.
"Why do the Foreign Ministry and judiciary not explain this? A death has happened and it should be explained," said Tavakoli.
"How can summoning a blogger (for questioning) be useful? Why do you
He urged authorities to look for "corrupt" officials who have been involved in the case, instead of mistreating bloggers.
Later Sunday, Iran's judiciary also said it would look into the death of Beheshti. The semi-official Mehr news agency cited a statement by the judiciary that it would investigate anyone who had a role in the case.
Lawmaker Ebrahim Nekou, who represents Beheshti's hometown of Robat Karim, also protested the his death. "I want to express my objection to killing of a blogger in my constituency while asking why the case was not announced to the officials of the town and to me."
The 35-year-old Beheshti was reportedly a factory worker. He was not a well-known activist.
The New York-based Committee to Protect Journalists said Saturday that Iranian authorities must release full details of the "suspicious death," and the State Department also called for a probe.
Dozens of bloggers and journalists have been arrested in widespread crackdowns in Iran in recent years.
In 2010, Iran's parliament played a major role in probing the deaths in detention of three people during the unrest that followed disputed 2009 elections. The inquiry led to the dismissal of several judicial and police officials.