Hundreds of protesters gathered in the Thai capital Bangkok on Saturday demanding the resignation of Prime Minister Paetongtarn Shinawatra, as her government faces rising anger over a border row with Cambodia.

The rally, the largest anti-government protest since her Pheu Thai party came to power in 2023, increases pressure on Paetongtarn, 38, who is battling to revive a faltering economy and keep a fragile government coalition together ahead of a potential no confidence vote next month.

Protesters waved flags beside Victory Monument, a war memorial at a busy intersection, in a demonstration organised by the United Force of the Land, a coalition of largely nationalist activists who have rallied against other Shinawatra-backed governments over the last two decades.

While the past protests did not directly cause the downfall of those governments, they built up pressure that led to judicial interventions and military coups in 2006 and 2014.

The political turmoil in Thailand threatens to further damage the country's struggling economic recovery.

Paetongtarn said on Saturday that she was not concerned about the protest and had instructed authorities to ensure the gathering was peaceful.

"It's within people's rights and I will not retaliate," she said.

The prime minister, who now controls a slim majority coalition following the exit of former partner Bhumjaithai Party last week, could face a no confidence vote when parliament reconvenes next week.

Bhumjaithai Party last week withdrew its support for the government citing the risk of a loss of Thai sovereignty and integrity after a leaked phone conversation between Paetongtarn and Cambodia's former premier Hun Sen.

During the call, Paetongtarn appeared to seek to appease the veteran Cambodian politician and criticised a Thai army commander, a red line in a country where the military has significant clout.

She has apologised for her comments.

The prime minister also faces judicial scrutiny after a group of senators petitioned the Constitutional Court and a national anti-graft body with a wide remit to investigate her conduct over the leaked phone call.

Decisions from either bodies could lead to her removal. Hun Sen, a former ally of the Shinawatras, made an unprecedented public attack on Paetongtarn and her family in an hours-long televised speech on Friday, calling for a change in government in Thailand.

The Thai foreign ministry described the speech as "extraordinary" while insisting that Thailand prefers to use diplomacy to resolve the escalating bilateral dispute.