Thais voted Sunday in an election pitting the popular reformists who came first last time against the conservative who ended up as prime minister, with ex-leader Thaksin Shinawatra looming large from his prison cell.

The Southeast Asian nation's next government will need to contend with anaemic economic growth -- the tourism sector vital but arrivals yet to return to their pre-Covid highs.

Multibillion-dollar transnational cyberscam networks operate from several neighbouring countries, and a longstanding border dispute with Cambodia erupted into deadly fighting twice last year.

"We need a strong leader who can protect our sovereignty," said Yuernyong Loonboot, 64, the first voter to cast his ballot at a polling station in Buriram, the hometown of incumbent prime minister Anutin Charnvirakul.

"Living here, the border conflict has made me anxious. War was never something we used to think about."