Put on a red shirt and join a political rally, and chances are you'll be accused of taking a bribe. Are you on the payroll of Thaksin Shinawatra, or have you ever accepted any money from him?

"No, none," was the simple reply of Dr Weng Tojirakarn, 57, a former leader of the pro-Thaksin Democratic Alliance against Dictatorship (DAAD).

"I am no lackey of Thaksin," he told The Nation, "but I stood with the red shirts [DAAD] to oppose the junta-sponsored charter [in 2007]. Followers of Thaksin were against the [2006] coup and have been fighting for a democratic system with the King as constitutional head. I have no problem with that. We must look at how the DAAD evolves."

Weng, a physician who specialised in family medicine, is quick to point out that he heavily criticised Thaksin in public prior to his break with the anti-Thaksin group that eventually morphed into the People's Alliance for Democracy (PAD).

Thaksin's avoidance of tax on the sales of Shin Corp shares in early 2006 "wasn't civil", he said, even if the law didn't require the then PM (now a convicted fugitive) to pay.

He broke with people like PAD co-leader Maj-General Chamlong Srimuang, with whom he joined hands in the fight against the military crackdown in May 1992, and the rest of the yellow-shirt camp, for reasons of principle, he said.

The final straw came after the proto-PAD called for a royally appointed prime minister and PAD co-leader Sondhi Limthongkul chose a night in February to call for military intervention.

"I declared [that I had left the group], and the newspapers reported it ... If friends behave like neo-Nazis, are selfish or corrupt, then I have to sever that friendship.

Weng was the first person to lodge a terrorism charge against the PAD after the group occupied two Bangkok airports for a week, threatening to bring the economy to its knees.

"I think they are," he said, when questioned on whether PAD members warranted the label "terrorists".

This uncompromising trait was evident from the earliest days of Weng's career as a political activist. At the time of the October 14, 1973 student uprising he was in his fifth year at Rama Hospital medical school and secretary-general of the Medical Students Centre of Thailand. His decision to allow pro-democracy groups to use the medical school as their ad-hoc office was crucial to their campaign against the military.

A son of poor Chinese migrants, Weng was bright enough to be accepted at the famous Triam-udom preparatory school.

He counted himself a disciple of the late monk and scholar Buddhadasa Bhikku, whose writings were an early influence and led him to devote much of his time to the fight for democracy and against poverty.

"I started with the question 'What are we born to do?' To rid ourselves of our selfishness is the answer."

Political turmoil after the October 6, 1976 massacre pushed Weng into the jungle, where he joined the medical unit of the Communist Party of Thailand, operating on his wounded comrades. Six years on, the battle lost, he returned to his native city, Bangkok.

He remained politically active and in 1992 teamed up with Chamlong and like-minded individuals such as Dr San Hattirat (one of his former medical lecturers) to form the Confederation for Democracy, which helped oust General Suchinda Kraprayoon as prime minister after the "Black May" uprising.

"I didn't think it was right for Thailand to revert to a military state. We were halfway to democracy."

Weng was deeply disappointed by what he saw as the soft and silent military intervention that contributed to the setting up of the Abhisit Vejjajiva government earlier this month.

"I think the 19 September, 2006 coup is still reverberating. The installation of the Abhisit government is just one more step towards the coup-maker's original purpose to destroy the democratic system with the King as head and replaced it with a strong bureaucracy. The PAD is a tool of the bureaucratic system. It ousted Samak [Sundaravej] and Somchai [Wongsawat] and declared it wanted 70 per cent [appointed members of Parliament] and 30 per cent [elected].

"The military's actions could be called a silent coup; that is, instead of tanks and guns, they "requested cooperation". The reality is that they're behind [the new government]."

Using a medical analogy, Weng said Thai democracy was suffering from a "septic infection" which had spread into the veins.

We still have an immune system fighting the infection, though, he added.

"It's made up of the people who love democracy."