TONGI (AFP) - A record four million Muslims gathered for prayers Sunday on the banks of a river in Bangladesh at the climax of the largest annual Islamic event after Haj, police said. The annual three-day Bishwa Ijtema, or World Muslim Congregation, concluded after an Indian imam led Zohr prayers. The gathering, at which Muslims pray and listen to religious scholars, was first held in the 1960s and was launched by Tableegh Jamaat, a non-political group that urges people to follow Islam in their daily lives. Deputy commissioner of police Khandaker Rafiqul Haq said at least four million people joined the final prayers, including the country's president, PM and the leader of the opposition. "This is the biggest crowd we have ever seen at the Bishwa Ijtema," Haq said, adding security had been tight with 11,000 police on guard since the devotees, many of them carrying beds and cooking utensils, started to congregate.