Protests with music festivals Photograph:( AFP )
PM Prayuth's spokesman said the prime minister feared the protests, which have spread across the country of 70 million, could be used by troublemakers seeking to instigate violence.
Thousands of pro-democracy protesters took over a major Bangkok intersection on Sunday, defying a ban on gatherings and stern warnings from authorities for the fourth consecutive day.
Prime Minister Prayuth Chan-ocha, a former junta leader the protesters seek to oust, is concerned about the spreading protests and the government wants to talk, his spokesman said.
The youth-led movement has suffered several blows this week, with scores arrested after demonstrators surrounded a royal motorcade and flashed a pro-democracy salute to Queen Suthida during a Wednesday protest.
The government reacted by imposing "serious" emergency measures banning gatherings of more than four and allowing for the arrest of protest leaders, many of whom are calling for the removal of Prayuth, a former military chief first brought to power in a 2014 coup.
Prayuth's spokesman said the prime minister feared the protests, which have spread across the country of 70 million, could be used by troublemakers seeking to instigate violence.
Police also deployed water cannon against unarmed demonstrators on Friday in Bangkok's central shopping district in an escalation of tactics that drew outrage across Thai society.
But the crackdown has emboldened the movement's mostly young supporters who have turned up in large numbers to daily guerrilla protests around Bangkok.
The locations are announced an hour before to outwit authorities, who shut down much of the city's Skytrain and underground rail services to discourage people from joining in.
Thousands descended on the major traffic thoroughfare from 4:00 pm (0900 GMT) shouting "Free our friends" while carrying posters of arrested activists.
Among their demands is the abolition of a draconian royal defamation law -- which shields King Maha Vajiralongkorn from criticism -- and a call for the monarch to stay out of the country's turbulent politics.
Once-taboo in Thailand, the issue of royal reform demanded by protesters is one of the biggest challenges facing the kingdom's conservative military-aligned government.
The social media-savvy protesters have also harnessed unorthodox ways of spreading their messages, sending alerts through newly formed groups on Telegram -- a secure messaging app -- and taken tips from Hong Kong's pro-democracy protests.
Police made no immediate steps to intervene as protesters took over Victory Monument and Asok, two of Bangkok's most important transport hubs. Police said there were around 10,000 people at Victory Monument alone. A spokesman said there was no plan to suppress the protest there.
During demonstrations by tens of thousands of people at multiple points across Bangkok on Saturday, protesters painted a flag on the road with "Republic of Thailand" written across it. The writing was painted out overnight.
The government banned demonstrations in Bangkok on Thursday.
Across Thailand, demonstrations were being organised in at least 19 other provinces on Sunday. Solidarity protests were also being held or planned in Taiwan, Denmark, Sweden, France, the United States and Canada.
(with inputs from agencies)