Police have used tear gas against thousands of protesters calling for the overthrow of the prime minister in the Thai capital, Bangkok.
At least 10,000 protesters gathered, demonstrating against the government of Yingluck Shinawatra, the sister of the deposed former prime minister.
The rally was organised by a group who accuse Ms Yingluck of being a puppet of her brother, Thaksin Shinawatra.
At least seven police officers were reported wounded in clashes.
Anti-riot police carrying plastic shields fired tear gas at protesters who tried to climb over concrete and barbed wire barriers blocking entry to the rally site, Bangkok's Royal Plaza, near the parliament.
The rally was not banned but police blocked demonstrators from accessing some streets near government buildings, says the BBC's Jonah Fisher in Bangkok.
"We used tear gas because protesters were blocking police and did not comply with the security measures we put in place," police spokesman Piya Uthaya told a local TV station, according to Reuters.
Police said they had seized various weapons, including knives and bullets, as protesters arrived.
The demonstration, which has now ended, was organised by a new group calling itself Pitak Siam - or Protect Thailand.
Led by a retired army general, the group accuses Ms Yingluck's administration of corruption and ignoring insults to the revered monarchy.
"I promise that Pitak Siam will succeed in driving this government out," former Gen Boonlert Kaewprasit said in his address to the rally.
"The world will see this corrupted and cruel government. The world can see the government under a puppet," he said later.
The group has attracted the support of various royalist groups including "yellow shirt" members of the People's Alliance for Democracy (PAD) who helped destabilise governments either led or backed by Thaksin Shinawatra in 2006 and 2008.
He remains a deeply divisive figure in Thailand. Ousted in a 2006 military-backed coup, he fled the country in 2008 shortly before being found guilty of abuse of power.
Earlier this week, Ms Yingluck, who was democratically elected in 2011 with a large majority, ordered nearly 17,000 police to be deployed during the rally and invoked a special security law.
"They [the government] like to claim they got 15 million votes. I'm here to show I was not one of them. So don't count me in. I didn't choose you," one unnamed protester told the Associated Press.