Who were the shadowy gunmen firing on troops in Bangkok's bloody
riots last weekend, and who fired the grenades?

The answers to those questions could point to the emergence of a dangerous split within Thailand's armed forces, one that could spark more bloodshed unless the beleaguered government calls elections promptly to defuse the political tensions.

Saturday's clashes, which killed 21 people and wounded hundreds, were not only Thailand's worst riots in 18 years. They may have taken the country a step closer to the worst-case scenario in its five-year-old crisis: a fissure in the military along social and political fault lines dividing the country.

NONEAlthough the city has since calmed down, tens of thousands of
anti-government 'red shirt' protesters remain on the streets of Bangkok demanding Prime Minister Abhisit Vejjajiva dissolve parliament.

Analysts say that large numbers of soldiers of lower ranks and some senior officers have long sympathised with the mostly rural and working-class 'red shirt' goverment behind more than a month of protests demanding immediate elections.

Many of the military's top brass are at the other end of the political
spectrum, allied with royalists, business elites and the urban middle
classes who wear yellow or pink at counter-protests and broadly back the 16-month-old government.

An army official who asked not to be identified said many mid-ranked and senior officers allied with Thaksin during his 2001-2006 administration were idelined, and are now throwing their weight behind the 'red shirts' to win power back.

Fissure in the military

A high-level source close to Prime Minister Abhisit described the 'red
shirt' movement as operating with two distinct fronts - the peaceful, non-violent protesters who staged a series of rolling street rallies in Bangkok since March 14 and a separate wing led by former and current generals in the army.

The fissure in an institution central to Thailand's power structure is
deepening uncertainty over the outlook for South-east Asia's second-largest economy, in part because neither side prevailed on Saturday, leaving two groups with military muscle at odds with each other.

Government and military sources said former army chief Chavalit
Yongchaiyudh, a former prime minister and close ally of Mr Thaksin, led other current and former generals in providing support to the 'red shirts'.

NONEChavalit has denied involement in Saturday's protests, which marked a violent escalation from the pattern of rallies seen during Thailand's
polarising political crisis.

TV footage showed some protesters armed with assault rifles or machine guns. M79 grenades were fired at soldiers. Grainy photographs showed at least one sniper positioned in a building.

The coalition government, which came to power in a 2008 parliamentary vote with tacit backing from the military's top leaders, says its troops only aired in the air. It has not been able to explain how at least nine protesters died from high-velocity gunshot wounds.

Publicly, the government blames a 'third hand' for stirring up the
violence. Privately, it says arms and extra forces were supplied by
pro-Thaksin renegades who they believe also targeted and killed a key military figure on Saturday, a colonel who suppressed a red shirt protest last year.

Worsening split

There is no doubt that Chavalit is a protagonist in the political drama now unfolding: immediately after Saturday's mayhem he called on Abhisit to dissolve parliament.

In October, Chavalit became chairman of the red shirts' parliamentary wing, the Puea Thai Party. He then persuaded scores of retired soldiers to join with him in what was seen as a move to create divisions in a normally rock-solid institution.

NONEHe made headlines last year by traveling to Cambodia for discussions with Cambodian Prime Minister Hun Sen, who days later infuriated Thailand's leaders by offering Thaksin a job as economic adviser and a base in Cambodia.

The worsening split, government sources say, is transforming life at a military base where Mr Abhisit and other senior cabinet officials now regularly meet, and sometimes sleep. Officials say their plans are being leaked from the base, the 11th Infantry Battalion of the Royal Guard.

It is unclear how far the military and its backers will go to save the
government and how far they will resist the re-emergence of Thaksin's allies, who would stand a good chance of returning to power in an election.

Much depends on an internal jostle for power in a country where the military is closely aligned with the monarchy and at a time when 82-year-old King Bhumibol Adulyadej has been in hospital since September, adding another element of uncertainty.

- Reuters