Thai riot police clashed with protesters on Tuesday, injuring hundreds of people, as campaigners intensified their four-month bid to unseat the government.

The Thai military ordered unarmed troops to patrol the capital Bangkok on Tuesday to keep order after a day of clashes between police and protesters who want the government to resign.

Army spokesman Col. Sansern Kaewkamnerd said police have enlisted the military's help in containing protesters from the People's Alliance for Democracy, a coalition of coalition of businessmen, academics and activists.

Sansern said the troops would not carry firearms.

Violent clashes between police and protesters on Tuesday left more than 380 people injured, at least 48 of them seriously. One woman protester died and a car bomb near parliament killed one man.

Early Tuesday, the violence began when police cleared the street outside parliament, where protesters had set up a blockade to prevent lawmakers from leaving.

Violence erupted again in late afternoon when the demonstrators expanded their protest and police fired tear gas to break through the crowd.

During the clashes, the protesters regrouped repeatedly. Protesters also set fire to parked cars, trucks and vans.

Thousands of demonstrators have occupied the grounds of the prime minister's office for the past six weeks trying to force the government to resign because they think it is too closely aligned with Thaksin Shiniwatra, the former prime minister overthrown in a coup two years ago.

Somchai Wongsawat, Thailand's newest prime minister and Thaksin's brother-in law, was expected to make a major policy speech in parliament on Tuesday.

Earlier, deputy prime minister Chavalit Yongchaiyudh resigned in an effort to take responsibility for the violent clashes. He had ordered police to use restraint against the protesters.

Agriculture Minister Somsak Prisananantakul said Chavalit took partial responsibility for the clashes in his resignation letter.

Chavalit, in charge of security, was seen as an important figure in helping the government to resolve the ongoing political crisis.

With files from the Associated Press and Reuters