Each day for two weeks, demonstrators have taken to the streets by the tens of thousands, blocking traffic at main avenues and repeatedly isolating the city from the rest of the country. Their demands range from the nationalization of the oil industry to a constitutional assembly.

They also oppose referendums called by four of the nation's regions to decide on greater autonomy.

As the legislators arrived in the congressional building at the central Murillo plaza, elsewhere in the city police used tear gas and water cannons to scatter protesters.

The demonstrators - peasants, miners, students - blocked traffic at one of the city's major intersections with pieces of pavement and burning tires. Roadblocks are a traditional form of protest in Bolivia, and wreak havoc on local economies.

This latest round of protests has lasted two weeks, and the roadblocks and angry demonstrations have affected mainly this city of 800,000 people, with the rest of the nation remaining calm. Downtown La Paz has been brought to a standstill for hours every day.

There were no reports of injuries or arrests in Tuesday's demonstrations.

On Monday, President Carlos Mesa accused radical ''minority groups'' trying to destabilize democratic rule.

During the protests, led by Congressman Evo Morales, many demonstrators chant slogans demanding Mesa's resignation, but the president has vowed to remain in power until the end of his term in August 2007.

Tuesday's congressional session was to discuss a bill that would decide how greater autonomy would be granted to Bolivia's regions, a highly sensitive matter. Regional rivalries often erupt between the country's richer east and the impoverished west, with a large indigenous population.