Thai anti-government protesters have surrounded the stadium where candidates were due to register to stand in February’s elections.
They say political reform is needed before elections take place.
On Sunday, tens of thousands took to the streets of the capital Bangkok, calling on the government to step down.
PM Yingluck Shinawatra, who called the polls in December try to end the rallies, urged protesters to respect the “democratic system”.
The main opposition Democrat Party has said it would boycott February’s elections.
Protest leader Suthep Thaugsuban, who was previously a senior Democrat Party politician, said on Sunday: “We disagree with the election. We want the country to be reformed before the election.”
He urged protesters to gather outside Bangkok’s Din Daeng Thai-Japan Stadium, where candidate registrations were set to take place, on Monday.
“If you want to apply for candidacy, you must walk past our feet first,” Suthep Thaugsuban said.
Political parties began registering their candidates at a local police station instead, while protesters responded by surrounding the police station as well, correspondents say.
Yingluck Shinawatra dissolved parliament and called an election on December 9, after more than 150,000 demonstrators took to the streets calling for her government to step down.
On Sunday, Yingluck Shinawatra told reporters that elections must take place, and urged protesters to express their views at the ballot box.
She said: “If we don’t hold on to the democratic system, what should we hold on to?”
“If you don’t accept this government, please accept the system,” Yingluck Shinawatra added.
Yingluck Shinawatra’s Pheu Thai Party won the last election in 2011, and has a majority in parliament. However protesters say her brother – ousted former leader Thaksin Shinawatra – remains in charge.
The protesters also accuse the Pheu Thai Party of using public funds irresponsibly to secure votes.
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