An Iranian lawmaker says about 3,700 people have been arrested in anti-government protests across Iran, a much higher number than previously estimated.
Tehran lawmaker Mahmoud Sadeghi announced the figure Tuesday in the state-run ICANA news agency.
He said the fact that protesters were arrested by a number of different security services made it difficult to get an accurate tally of the detained.
Rights group Amnesty International is calling on Iranian authorities to immediately investigate reports that at least five people have died in custody after a crackdown on anti-establishment protests over the past two weeks.
Amnesty said in a statement Tuesday that prison conditions in Iran are "nightmarish" and include the use of torture. Magdalena Mughrabi, Amnesty's deputy director for the Middle East and North Africa, called on authorities in Iran to "immediately launch an independent, impartial, and transparent investigation, including independent autopsies" of those who died.
She said those suspected of having any responsibility for these deaths should be suspended from their positions and prosecuted in proceedings that respect international fair trial standards and do not include the death penalty.
Amnesty said since the report emerged Monday that protester Sina Ghanbari died while being held in Tehran's Evin prison, four more reports of deaths have emerged.
Two of those deaths were reported to be in the same place Ghanbari died, in the prison's "quarantine" section, where detainees are held for processing immediately after arrest. The names of those victims are unknown, according to human rights lawyer Nasrin Sotoudeh.
Two others, Vahid Heydari and Mohsen Adeli, also died in custody, according to Amnesty. It says the families of the victims dispute the official report that they committed suicide.
Amnesty called on Tehran to inform family members about detainees' whereabouts, allow them to visit their loved ones, and ensure legal representation for those arrested.
"Nobody should face reprisals for inquiring about the whereabouts of a loved one or seeking truth about their fate," Mughrabi said.
Sadeghi, the Iranian lawmaker, said he was told Iranian protester Ghanbari, 22, committed suicide while in custody. Another lawmaker, Tayyebe Siavashi, said the detainee had been arrested in Tehran.
Details of the incident were not immediately clear, but it was thought to be the first death of a protester in custody as a result of the current demonstrations sweeping the country.