At least 2.5 million Muslims joined prayers on Sunday near the Bangladeshi capital as part of the second largest annual Islamic festival after the Hajj to Mecca, officials said.
The normally congested streets of Dhaka were empty as devotees left work to gather on the banks of the river Turag for the end of the first phase of the Biswa Ijtema, or World Muslim Congregation.
The gathering, at which Muslims pray and listen to religious scholars, was first held in the 1960s at Tongi, some 30 kilometres (18 miles) North of Dhaka.
Dressed in traditional Islamic robes and caps, devotees set up prayer mats beneath a canopy stretching more than a kilometre while hundreds of thousands of people filled the open space available for the final prayer.
District police chief Mahfuzul Haq Nuruzzaman said at least 2.5 million devotees including thousands of foreigners attended a last prayer session lasting 20 minutes and led by a cleric from New Delhi.
"Devotees have filled up every space found on the roads, rooftops, boats and buses," Nuruzzaman said, adding the Bangladesh president and the Prime Minister joined prayers capping the three-day long first phase of the festival.
Bangladesh is the world's third-largest Muslim-majority nation, with Muslims making up nearly 90 percent of its 146 million population.
Launched by Tablig Jamaat, a non-political group that urges people to follow the tenets of Islam in their daily lives, the event is second biggest global gathering of Muslims.
Gazi Mohammad Sanaullah, who edits a special bulletin on the congregation, said the organisers are holding the prayer meeting in two phases to accomodate more devotees some of whom travel from remote villages.
The three-day long second phase will start on January 28.