As voting booths across Thailand's capital closed at 4pm, two separate surveys showed Mr Apirak Kosayodhin looking comfortable for a second term.

A poll by Suan Dusit put Democrat Party candidate Apirak at 52.08 per cent while an ABAC poll reported he garnered about 44 per cent of the vote.

Mr Prapas Chongsa-nguan, the candidate for the prime minister's ruling People Power Party, was trailing in second place with 23.23 per cent, according to Suan Dusit, and 33.9 according to ABAC.

Mr Prapas left his job running the city's underground railway to go for the job, voted for every four years.

'I will wait for the actual results,' Mr Prapas told Thai television. 'The exit polls don't prove anything.'

Suan Dusit said former massage parlour owner Mr Chuwit Kamolvisit, who showed his mettle as a combative figure by punching a television interviewer on Thursday - had won third spot with 12.1 per cent of the vote.

'I'm proud of all the votes I received today even though I will not become the governor,' Mr Chuwit told Thailand's Channel 9.

But ABAC said academic Mr Kriangsak Charoenwongsak had achieved 12.64 per cent and third place.

Of the 12 million Bangkok residents, more than 4 million were eligible to vote for one of 16 candidates in Sunday's elections.

Bangkok's city clerk said he believed there had been a high turnout since 9am on Sunday morning.

'I saw that people were enthusiastic to exercise their right at the election. They stood in line waiting to vote at several polling booths. I expect 70 per cent of the eligible voters to have voted,' Mr Pongsak Semsant told a television interviewer.

Aside from the controversy surrounding Mr Chuwit's punch, the race to be governor saw unusually high drama this year.

Another candidate, Ms Leena Jangjanya, bathed in a canal to highlight the lack of clean water in the city but the stunt turned to tragedy when her chief campaign adviser drowned. -- AFP