Friends and family of missing hajj pilgrims have been searching hospitals and pleading online for news, fearing the worst after hundreds died during the annual rites in Saudi Arabia. Arab diplomats on Tuesday told Agence France-Presse at least 550 pilgrims had died this year, the majority due to heat-related illnesses after temperatures reached 51.8C (125F) in Mecca, Islam’s holiest city. The total number of people reported dead so far is 645, according to an AFP tally of figures released by various countries. About 1.8 million people attended the pilgrimage. The hajj is one of the five pillars of Islam and all Muslims with the means must complete it at least once. Its timing is determined by the Islamic lunar calendar, shifting forward each year in the Gregorian calendar. For the past few years, the mainly outdoor rituals have taken place during the sweltering Saudi summer. According to a Saudi study published last month, temperatures in the area are rising 0.4C (0.72F) each decade. Human-caused climate breakdown is making every heatwave in the world more intense and more likely to happen. The burning sun and suffocating hot weather were relentless on Tuesday in Mecca and the sacred sites in and around the city, according to the Saudi National Centre for Metrology. Many pilgrims, particularly elderly ones, collapsed and required medical assistance because of the heat. Mabrouka bint Salem Shushana, of Tunisia, in her early 70s, has been missing since the climax of the pilgrimage on Saturday at Mount Arafat, her husband, Mohammed, told AFP on Wednesday. Because she was unregistered and did not have an official hajj permit, she was unable to access air-conditioned facilities that allow pilgrims to cool off after hours of outdoor prayers, Mohammed said. “She’s an old lady. She was tired. She was feeling so hot, and she had no place to sleep. I looked for her in all the hospitals. Until now I don’t have a clue.” He is not the only one desperate for information. Facebook and other social media networks have been flooded with pictures of the missing and requests for information. The searchers include family and friends of Ghada Mahmoud Ahmed Dawood, an Egyptian pilgrim unaccounted for since Saturday. “I received a call from her daughter in Egypt begging me to put any post on Facebook that can help track her or find her,” said one family friend based in Saudi Arabia, who spoke on condition of anonymity because he did not want to anger Saudi authorities. “The good news is that until now we did not find her on the list of the dead people, which gives us hope she is still alive.” The figure of 550 dead provided by diplomats on Tuesday came from the hospital morgue in Mecca’s al-Muaisem neighbourhood, one of the biggest in the city. It included 323 Egyptians and 60 Jordanians, said the Arab diplomats who briefed AFP on the figures, one of whom noted that nearly all the Egyptians died “because of heat”. Deaths have also been confirmed by Indonesia, Iran, Senegal, Tunisia and Iraq’s autonomous Kurdistan region, though in many cases authorities have not specified the cause. On Wednesday, an Asian diplomat told AFP there were “around 68 dead” from India and that others were missing. “Some (died) because of natural causes and we had many old-age pilgrims. And some are due to the weather conditions, that’s what we assume,” he said. Saudi Arabia has not provided information on deaths, though it reported more than 2,700 cases of “heat exhaustion” on Sunday alone. Last year more than 200 pilgrims were reported dead, most of them from Indonesia. Each year, tens of thousands of pilgrims attempt to perform the hajj through irregular channels as they cannot afford the often costly official permits. This had become easier since 2019 when Saudi Arabia introduced a general tourism visa, said Umer Karim, an expert on Saudi politics at the University of Birmingham. “Before, the only people who could have done that were residents of the kingdom, and they know the situation,” he said. “For these tourist visa guys, it’s like being on the migrant route without any idea of what to expect.” Even pilgrims who have official permits can be vulnerable. Houria Ahmad Abdallah Sharif, a 70-year-old Egyptian pilgrim, has been missing since Saturday. After praying on Mount Arafat, she told a friend she wanted to go to a public bathroom to clean her abaya, but she never came back. “We’ve searched for her from door to door and we have not found her,” said the friend, who also spoke on condition of anonymity. They added: “We know many who are still searching for their family members and relatives and they are not finding them, or if they are finding them they are finding them dead.”