Hundreds of thousands of Turks jammed a waterfront square in Istanbul, in what appeared to be the largest pro-government demonstration since last month's failed coup.
Prime Minister Binali Yildirim told the August 7 rally that a U.S.-based cleric whom the government has repeatedly accused of sedition would be brought to Turkey. He vowed that the cleric, Fethullah Gulen, would face justice.
"Let all of you know, the leader of this terrorist group will come to Turkey and pay for what he did," Yildirim told the crowd.
Leaders of opposition parties were also reportedly asked to address the crowds, although the pro-Kurdish Peoples' Democratic Party was not invited.
Since the July 15 coup attempt, tens of thousands of government, educational, and civil-service workers have been dismissed, and thousands have been arrested as Turkish authorities crack down on suspected coup plotters.
Many are suspected of having ties to Gulen, who has denied Turkish accusations that he organized the coup.
The scope of the crackdown has alarmed European countries and rights groups. President Recep Tayyip Erdogan has lashed out at such criticism, and complained of a lack of support from the West.