Iranian President Hassan Rouhani used a major United Nations speech on Saturday to demand an investigation into a crush that killed more than 700 people at the annual haj pilgrimage in Saudi Arabia.The fact that Rouhani used a UN summit meeting on global development goals to reiterate Iran's outrage over the haj tragedy was a sign that Tehran does not intend to tone down criticism of its regional rival Saudi Arabia. Both Iran and the Saudis see themselves as leaders in the Muslim world.In his speech to the 193-nation UN General Assembly, Rouhani emphasized the need for an investigation into "the causes of this incident and other similar incidents in this year's haj." He described the crush as "heart-rending."Saudi Arabia suggested on Friday pilgrims who ignored crowd control rules bore some blame for the incident. Saudi King Salman ordered a review of haj plans, and Health Minister Khalid al-Falih said an investigation would be conducted.Iran has repeatedly voiced outrage at the deaths of 131 of its nationals at the world's largest annual gathering of people.Saudi Foreign Minister Adel al-Jubeir accused Iran of playing politics with the tragedy.