BANGKOK: A convoy of Thai "Red Shirts" headed to their northern heartland Saturday for rallies marking four years since the coup that ousted Thaksin Shinawatra and four months since deadly protests ended.

The procession of 80 cars, vans and pickup trucks snaked out of the Thai capital as 200 members of the anti-government movement made their way to Chiang Mai, protest leaders said.

Demonstrators are converging on Chiang Mai, the former stronghold of the fugitive former prime minister Thaksin, for a rally Sunday marking the 2006 coup that swept him from power.

Reds are also Sunday set to gather at Bangkok`s Ratchaprasong intersection that was the focus of their April-May protest, during which 91 people were killed and nearly 1,900 were injured, to release 10,000 red balloons.

Somyot Prueksakasemsuk, leader of one Red faction, said the rallies would call for authorities to free all political prisoners, reform the courts with the introduction of a jury system, as well as other land and economic measures.

"Our first demand is to release all political prisoners," he said.

Somyot said he expects 10,000 protesters to join the demonstration in Chiang Mai -- compared to an official estimate of 1,000.

He said some prominent Red leaders, still at large and wanted by police over the April and May demonstrations, would find a way to address protesters from hiding.

On Friday 1,000 people gathered outside Bangkok`s remand prison to show solidarity with 19 senior Reds jailed for having key roles in the two-month protest that ended in a bloody army crackdown on May 19.

None has been convicted of any crime related to that rally.

Bangkok, which is still under a state of emergency along with six other provinces, will have an army-run command centre monitoring activities and there will be another in Chiang Mai, although the decree has been lifted there.

Authorities are also planning to be out in force, with about 900 police in charge of Chiang Mai and around 3,000 plain clothes and uniformed officers mobilised in Bangkok.

BDST: 1650 HRS, September 18, 2010