A Thai anti-government protest leader has been shot dead in Bangkok as demonstrators blocked advance voting for a disputed general election.

The protest movement's spokesman, Akanat Promphan, says Suthin Tharathin was giving a speech from a pick-up truck in the Thai capital when he was shot and killed.

"The government has failed to provide any safety and security for anybody today despite the emergency decree," he said, referring to a government order empowering police to control protests.

Bangkok's Erawan emergency centre confirmed one man had been killed and nine injured in the shooting in the city's suburbs.

Anti-government protesters forced the closure of 19 out of 50 polling stations in the Thai capital, Bangkok, on Sunday, disrupting advance voting for the disputed general election.

The country's election commission says protesters surrounded buildings, blocking officials from entering to hold advance voting in Bangkok and several southern provinces.

"Nineteen poll stations reported closed out of 50 in Bangkok," said Puchong Nutrawong, the secretary general of the election commission.

"Election officials at the poll stations could not go inside because of the protesters."

He added it was unclear how the advance votes not cast ahead of the scheduled February 2 election will be tallied.

Protesters have prevented commission staff from delivering ballot boxes to polling stations.

Candidates in 28 southern electoral constituencies have been unable to register for candidacy as protests disrupted registration.

A Thai man casts his vote at a polling station minutes before it got shut down by Thai anti-government protesters in Bangkok on January 26, 2014. ( AFP: Nicolas Asfouri )

Voters' rights 'taken away by protesters'

Sunai Phasuk, senior researcher for Human Rights Watch in Thailand, says across the country more than 400,000 people have been denied their right to vote.

He told Radio Australia's Asia Pacific that Thai voters were frustrated and angry by the blockade.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 4 minutes 52 seconds 4 m 52 s Thai voters angry over advance ballot blockade ( Sen Lam ) Download 2.2 MB

Thai anti-government protesters shut down a polling station at the Srieam Anusorn school in Bangkok on January 26, 2014. ( AFP: Nicolas Asfouri )

"They asked protestors: How [can] protestors who claim to be striving for greater democracy and greater respect of people and people's participation in politics [do] everything to contradict their ideological platform?

"What protesters did yesterday was contrary to a respect for democratic right to cast a ballot, which is the foundation that everyone is equal - one man, one vote.

"So if the protestors do not respect this one-man, one-vote principle, clearly they do not respect that we are all equal.

"And for that - the change that they are pushing for Thai politics - it's not a change for equality but the opposite of that."

More than two million people are registered for the advance vote ahead of next week's polls, which was called by prime minister Yingluck Shinawatra in an attempt to defuse rising political tensions after weeks of mass anti-government protests.

Advance voting is being held for those who are unable to take part in next Sunday's polls and is routine, although this time it is being seen as a litmus test for the possibility of holding the vote without violence.

Demonstrators have rejected the election and vowed to gather around polling stations.

The protesters have staged a so-called "shutdown" of Bangkok for almost two weeks, in an effort to disrupt the vote.

The prime minister is scheduled to hold a meeting on Tuesday with members of the election commission to discuss possible change of date for the election.

At least nine people have died and more than 500 injured since political violence started late last year, after the lower house of Thailand's parliament passed an amnesty bill appearing to benefit the prime minister's brother, former leader Thaksin Shinawatra.

The bill was later voted down in the Senate.

The Australian Department of Foreign Affairs and Trade advises travellers in Thailand to exercise a high degree of caution, and to avoid all locations where protests are occurring due to the risk of further violent attacks.

AFP/Kyodo