Iran's President Hassan Rouhani has used a speech at the UN to callfor an investigation into Thursday's stampede at the annual Hajj pilgrimage to Mecca.
The incident is the deadliest to hit the Hajj in 25 years, with 769 people dead, more than 130 of them from Iran, and 934 injured.
Mr Rouhani described the crush as "heart-rending".
Saudi Arabia's most senior cleric has defended the authorities, saying the stampede was "beyond human control".
King Salman has ordered a safety review into the disaster.
Iran and several other countries have criticised Saudi authorities for the way they handled safety issues.
Iran's outrage also has political motivations, as its battle with Saudi Arabia for regional influence sharpens week by week, correspondents say.