The spokesman said the army would try to negotiate with the protesters first, but if the effort failed, they would use teargas and water cannons to secure the area.

The surrender of UDD leaders and dispersing of protesters may mean an end, at least a halt, of Thailand's 20-day-long political turmoil since March 26, when the "red-shirts" led by UDD began to rally to push Abhisit to resign.

Last Sunday afternoon, Abhisit declared a state of emergency in Bangkok and some districts of five nearby provinces, citing the escalating violence of the protests, which on Saturday forced the then-ongoing ASEAN summit and related summits to be canceled in Pattaya.

After imposing the state of emergency, Abhisit had promised to restore order in the country in three or four days during the Songkran Festival, the water-splashing holiday which kicked off on Monday to coincide with the start of a urban war fight between protesters and the authorities.

Supporters of ousted Thai prime minister Thaksin Shinawatra queue to leave the Government House area while soldiers watch in Bangkok April 14, 2009. [Xinhua]

Violence in Thailand escalated Monday despite government troops attempted to gain control and restore order to the capital Bangkok.

At about 4:30 a.m. local time Monday morning, some 300 red-shirted protesters used a seized bus to crash soldiers stationed at Din Daeng District in north Bangkok. Soldiers fired warning shots into the air and used teargas to disperse the protesters. Abhisit later confirmed some 70 injured in the clash, with no death.

The "red-shirts" on late Monday morning began to block several main intersections including the Din Daeng Intersection, forcing more than 100 bus routes and medical services to bypass the area. The authorities also claimed the violence was incited by protesters who burnt buses, seized LPG tankers, intruded local markets, broke into banks and attacked soldiers as well as civilians throughout the day.