Thai opposition protesters have stepped up their campaign to disrupt upcoming elections, trying to block candidate registrations as part of efforts to banish Prime Minister Yingluck Shinawatra and her family from politics.
The main opposition Democrat Party, which has not won an elected majority in parliament in about two decades, has vowed to boycott the February 2 polls called by Yingluck after weeks of street rallies by her opponents.
Hundreds of demonstrators on Monday surrounded a stadium in Bangkok where representatives of political parties were trying to register to run in the polls ahead of the December 27 deadline.
The unrest comes a day after at least 150,000 people held anti-Thaksin mass protest in the capital, according to an estimate from National Security Council chief Paradorn Pattanatabut.
Organisers said the turnout was much higher.
It is the latest chapter in a years-old political crisis which broadly pits a Bangkok-based elite against mostly rural and poor supporters of Yingluck and her brother Thaksin Shinawatra, a divisive former premier who was ousted in a coup in 2006.
Despite the protests, more than thirty political parties managed to register at an alternative Election Commission venue, Al Jazeera's Florence Looi, reporting from Bangkok, said.
Election officials have already anticipated the blockade, and implemented a back-up system of registration, Looi said.
"So it would seem that the protesters have not been able to achieve their objective," she said. "The protesters don't want elections taking place, because they don't trust the process."
Representatives of Yingluck's Puea Thai party managed to get inside the stadium in the early morning before it was sealed off by protesters, party spokesman Prompong Nopparit said.
He said Yingluck was on top of the party's list of candidates - a position that would usually make her Puea Thai's pick for prime minister if it wins the polls.
Her candidacy is certain to anger the demonstrators, who want to rid Thai politics of the influence of her brother Thaksin - a billionaire tycoon turned premier whom protesters accuse of controlling the government from his home in Dubai.
The demonstrators' self-proclaimed People's Democratic Reform Committee is calling for an unelected "people's council" to be installed to oversee sweeping but loosely-defined reforms before new elections in around a year to 18 months.
They have vowed to rid Thailand of the "Thaksin regime" and oppose the election, saying it will only bring another government allied to the former premier, who fled the country in 2008 to avoid jail for a corruption conviction he contends is politically motivated.
The protesters have appealed for the support of the army, but the military has indicated it will not step in directly at this stage, in a country which has seen 18 successful or attempted coups since 1932.
Thaksin is adored among rural communities and the working class, particularly in the north and northeast. But the billionaire tycoon-turned-politician is reviled by the elite, who see him as corrupt and a threat to the revered monarchy.