Supporters and opponents of Prime Minister Prayut Chan-o-cha turned up in droves on Sunday for their respective political rallies, with the rival camps likely to square off again next month when the anti-Prayut event organisers plan another event in Chiang Mai.

Tanawat Wongchai, organiser of the anti-regime "Wing Lai Lung" (Run to Oust the Uncle), told the crowds at Suan Rot Fai or Vachirabenjatas Park that the run marked the start of the campaign to oust Gen Prayut from office.

He also said the next run is being scheduled in Chiang Mai on Feb 2.

"This is our first step. We will continue running to oust the Uncle this year," he said at the end of the event, using the word "Uncle" in reference to Gen Prayut.

The event's organisers claimed the event drew 13,000 participants, which included key figures from the opposition and political activists.

Future Forward Party (FFP) leader Thanathorn Juangroongruangkit, FFP list-MP and spokeswoman Pannika Wanich, and Prachachart secretary-general Thawee Sodsong were among the politicians who joined the anti-Prayut run.

Mr Thanathorn said the government will face more protests in the coming months and that the large turn-out yesterday was highly indicative of increasing political awareness about the regime's prolonged grip on power.

He said his participation in the activity was a message that he and the FFP stand with those calling for political change. Mr Thanathorn also denied the party was behind the organisation of the event.

"I'm here to show that we're fed up," said Paphatsara Netsang, a Thai who lives in Singapore but flew in for the rally.

"Nothing has changed. Everything is still the same. There's no economic improvement."

Across the city at Lumpini Park, thousands of people gathered to show support for Gen Prayut at another gathering called "Dern Cheer Lung" (Walk In Support of Uncle). The participants carried signs and banners with messages expressing firm support for the prime minister.

Haruethai Muangboonsri, a well-known singer and staunch supporter of the premier, said yesterday the group is prepared to launch a counter-rally if Gen Prayut's critics have other ones in the works.

She also insisted that Gen Prayut came to office through a democratic process following the general election last year.

"Don't twist it and say the prime minister is a dictator," she said.

Thitimon Cottan, 52, a state enterprise employee, said she joined the rally because she wanted Gen Prayut to continue serving the country. She said the prime minister brought back peace and order after political unrest, and that he had made many contributions toward the betterment of the country.

At the event, large boards were put up for the prime minister's supporters to attach sticky notes with messages of support. According to the event's organisers, the police estimated some 13,000 supporters of Gen Prayut turned up at Lumpini Park.

T-shirts and caps were distributed free of charge to the participants.

Parallel events for "Wing Lai Lung" also took place in several other provinces, including including Buri Ram, Phayao, Chiang Mai, Nakhon Pathom, and Nakhon Ratchasima.

The number of participants ranged from dozens to hundreds and the runs were said to be closely monitored by the police.

Despite their starkly opposing views, both events proceeded without incident.

Sontirat Sontijirawong, secretary-general of the ruling Palang Pracharath Party (PPRP), urged both camps to keep their political activities calm and avoid taking to the streets.

He said social rifts and political missteps should be avoided to stop the country from slipping back into a crisis.

"I'm not saying those activities are wrong but all sides are urged to look at the big picture and use mechanisms in the constitution [to solve problems]. Please do not take people to the streets," he said.

Anusorn Iamsa-ard, spokesman of the main opposition Pheu Thai Party, predicted that the protests will intensify across the country.

"The civil sector led by our youth has lit a spark. Pheu Thai and the opposition will move ahead with our no-confidence debate against the government. The administration is unlikely to stay in place past the first half of this year," he said.

Chaturon Chaisang, former chief strategist of the now-dissolved Thai Raksa Chart Party, wrote on his Facebook page that calls for the prime minister's ouster will soon gain momentum.