Shots have been heard in the Thai capital, Bangkok, where soldiers have moved to disperse anti-government protesters at a major junction.

A Reuters reporter on the Viphavadi-Rangsit thoroughfare saw protesters hurling stones and retreating into side streets as troops advanced.

An army spokesman said troops were using tear gas in the operation close to the landmark Victory Monument.

At least two people are confirmed to have been hurt in the clashes.

Emergency services told AFP news agency that 49 people had been injured.

'Soft measures'

An army spokesman, Col Sunsern Kaewkumnerd, said about 400 soldiers had moved against some 300 protesters at Din Daeng intersection.

Some protesters had responded by driving a car at the soldiers, he told AFP.

Col Kaewkamnerd was also quoted by Reuters as saying troops fired into the air first in response to tear gas and smoke bombs thrown at them by protesters, but "then fired real bullets".

"We will start with soft measures and proceed to harder ones," the army spokesman told AFP.

"We will avoid loss of life as instructed by the government."

The Thai authorities earlier declared a state of emergency after protests by supporters of ousted Prime Minister Thaksin Shinawatra, which stopped a major Asian summit in Pattaya.

Battle of wills

Earlier on Sunday, protesters broke into the interior ministry and at one point attacked a car they thought was carrying Prime Minister Abhisit Vejjajiva. He was not inside.

They blocked a number of busy road junctions and at least one railway, and took over buses and two armoured vehicles.

The collapse of the summit was a huge embarrassment to Prime Minister Abhisit Vejjajiva and he has vowed to restore order, says the BBC's Jonathan Head in Bangkok.

Our correspondent says that what began as a show of strength by the government's opponents two weeks ago has turned into a battle for control of the capital which neither side feels it can afford to lose.

Under the state of emergency, gatherings of more than five people can be banned, media reports can be censored and the army can be deployed to help police maintain order.

Last year, the government imposed a state of emergency on several occasions but the army refused to enact the measures.

That crisis eventually led to Mr Abhisit's government taking over from allies of Mr Thaksin.

Our correspondent in Bangkok says the problem for Mr Abhisit is that he rode to power on the back of protests that were just as illegal, and may look hypocritical if he only goes after the red-shirted protesters who embarrassed him.