Red-shirt supporters of former prime minister Thaksin Shinawatra from various northeastern provinces have begun converging on Thung Srimuang open ground in Muang district of Udon Thani province for a "bring Thaksin home" rally, reports said.
A large stage has been erected at Thung Srimuang. Police used mine detectors to scour the area around the stage and the open ground for bombs.
About 1,000 police have been deployed to provide security.
Kwanchai Praipana, leader of Udon Thani red-shirts, went up on the stage and vowed the make the rally the largest ever to demand the government bring fugitive Thaksin home from self-exile abroad.
He claimed about 100,000 people would attend the rally.
Pheu Thai MPs in the Northeast have been taking turns to speak on the stage.
Deputy Prime Minister Chalerm Yubamrung was scheduled to appear on the stage at 6pm to explain his reconciliation bill, filed with the House of Representatives yesterday by Pheu Thai MPs.