Former Thai prime minister Thaksin Shinawatra has called for the overthrow of the government after authorities imposed a state of emergency in Bangkok amid widespread protests.
His call came after armed soldiers were deployed across the Thai capital on Sunday, a day after "Red Shirt" movement anti-government protests forced the cancellation of a summit of Asian leaders in the beach resort of Pattaya.
He said: "The troops who have already come out can come and join the Red Shirts to help us to get democracy for the people.
"This is a golden minute. We will make history and there will be no more coups in Thailand. We have to help achieve democracy for all of us."
Thaksin, who was ousted in a 2006 coup, said on Sunday that he may return to Thailand and re-enter politics if the government moves to crack down on the opposition protests.
Tony Cheng, Al Jazeera's correspondent in Bangkok, said: "It's a major embarrassment to Thailand. They [the government] seem to be completely powerless to stop [the protests]."
"We've been seeing policemen putting on red shirts and coming here to join the rally.
"One wonders whether the prime minister does actually have control over the armed forces, he does appear to have lost control over the police," he said.
"The situation does seem to have calmed down considerably this evening."
Protest leaders told Al Jazeera that they would continue their protests, seeking the resignation of Abhisit Vejjajiva, the prime minister.
Thaksin exercising the nuclear option to the extreme.
But not really that much different than what the Democrats did before the coup and what the PAD did after the coup. People seem to forget that Abhisit was one of the leaders aligned with the PAD before the coup and was demanding that Thaksin resign and be replaced outside the law.
Abhisit has no moral authority. He doesn't have any authority apparently.
The chickens have come home to roost.