One dead in gun attack on Thai protesters

The victims, supporters of a militant faction of the opposition movement, were returning from a rally at a government complex in the north of the capital when they were fired on by unknown assailants.

The protesters want Prime Minister Yingluck Shinawatra to step down to make way for an unelected interim government to oversee reforms aimed at curbing the political dominance of her billionaire family.

A 52-year-old man was killed and four others were wounded, according to the city's Erawan emergency centre.

The splinter group that was attacked, the Network of Students and People for the Reform of Thailand, has often been at the vanguard of attempts to storm state buildings during five months of rallies seeking to oust Prime Minister Yingluck Shinawatra.

"The shooting lasted for around 2 minutes -- the convoy stopped and everyone took shelter as they raked bullets over the vehicles," group leader Uthai Yodmanee told AFP.

The dead man was a guard for the group and was shot as he stood on a truck passing along the expressway, he said, adding the gunmen appeared to be holed up in apartment blocks.

Thailand has been shaken by a series of grenade attacks and shootings, often targeting protesters, that have left 24 people dead and hundreds wounded in recent months.

The violence had eased since the rallies were scaled back at the start of March when demonstrators abandoned their occupation of major intersections in Bangkok and converged in a park in the city.

"According to our initial intelligence information, it definitely involved politics," said Paradorn Pattanatabut, a security adviser to the premier, of Tuesday's shooting.

"It is hard to control the situation," he said, adding that hardliners were mixed up in the deadly political crisis.

Thailand has seen years of political conflict and rival street protests by opponents and supporters of her brother, fugitive former premier Thaksin Shinawatra who was ousted in a coup in 2006 and lives overseas to avoid jail for a corruption conviction.

Observers say the festering political crisis is edging into a crucial new phase.

Yingluck testified Monday in front of anti-graft officials over negligence charges that could lead to her removal from office and a ban from politics.

She asked the National Anti-Corruption Commission (NACC) leading the probe to question 10 further witnesses and give her more time to make a full defence.

After considering the request NACC officials on Tuesday said it would question just three more witnesses but it stopped short of setting a date for the next hearings.

An indictment by the agency would trigger the prime minister's immediate suspension from office pending an impeachment vote in the upper house of parliament within weeks.

While the nine-stong NACC panel is an independent body, government supporters say it is politically biased against the administration.