Prayers and protests have been staged amid mounting fury over the deaths of more than 700 worshippers during a stampede at the annual hajj pilgrimage.
Iran led the criticism of Saudi Arabia saying that the organisers should "be held accountable" while a leading British Muslim declared the Saudi government needs to focus more on developing infrastructure for ordinary people performing hajj rather than building more luxury hotels.
There have been 719 deaths but that number is expected to rise and at least 863 people were injured, according to the Saudi civil defence directorate.
Thousands protested in the streets of Tehran where senior cleric Ayatollah Mohammad Emami Kashani angrily demanded Saudi Arabia hand over control of the event to the Organisation of Islamic Cooperation (OIC), the world's largest body of Muslim nations.
He said: "The Saudi government and authorities involved in hajj should appear before court and be held accountable.
"They should not lie and say, 'It was because this or that, the weather was hot, it was the pilgrims' faults'."
In a statement Iyad Madani, the secretary-general of the 57-nation OIC, hoped that "no party would seek to take advantage" of the pilgrimage to "divide rather than unite".
The hajj pilgrimage is a main pillar of Islam and two million people from more than 180 countries are taking part in the five-day event which ends on Saturday.
Imam Qari Asim, speaking after special prayers were held for the victims at Yorkshire's Leeds-based Makkah Masjid, described the hajj as a "logistical nightmare" which needs a lot of manpower and infrastructure to be properly managed.
He said: "The Saudi government is very good in terms of building huge hotels and other things around Mecca but, in terms of investing in the actual buildings where the rituals take place, this is hugely important."
The crush happened in a morning surge of pilgrims in Mina, about three miles east of Mecca, when they were making their way towards a large structure overlooking three columns where pilgrims carry out a symbolic stoning of the devil by throwing pebbles.
Mr Asim said: "It's really difficult for elderly and frail people. And there are a number of people who have never gone abroad. For them it's really difficult to relate to that environment.
"You see so many people who are kind of lost. You are at the height of your emotions but at the same time you are physically drained. All of that contributes to people falling over each other."
Saudi Arabia's Crown Prince Mohammed bin Nayyef, who chairs the hajj committee, has begun an immediate inquiry into the tragedy, with "fast" results promised.
Khalid Anis, of the Islamic Society of Britain, said: "Am I confident that it will be looked at and analysed properly? No. Because it's already turned into a blame game and we have no idea of the story."
Frustrations boiled over as the nations began the grim task of recording their dead and missing citizens. It is not yet known how many of the dead are British.
It is estimated that around 25,000 British nationals head from the UK to Saudi Arabia for the event, according to Abta, the travel association.
Pakistan has said that at least 236 of its pilgrims are unaccounted for while both Egypt and India state that 14 of its citizens have been killed.
Early estimates record that at least four Turks, three Indonesians, three Kenyans and seven Pakistanis were killed. Authorities in West Africa said 30 pilgrims from Mali and five from Senegal also died.