Bolivian President Carlos Mesa warned Tuesday of possible intervention of the armed forces, should the political and social crisis in the country worsens.

Calling for peace and dialogue with opponents, Mesa said that in an extreme case, the military will put down any attempt to destabilize the country. It is the right of the Bolivian nation to defend itself, he said.

Unrest spilt over to La Paz, the seat of government, on Tuesday as protests escalated in the neighboring city El Alto, according to reports from La Paz.

Thousands of demonstrators marched through downtown La Paz to rally at Murillo Square, where the executive and legislative departments are located, demanding the nationalization of the oil industry and the rejection of autonomy demands by four regions.

The protesters cut off airport access and blocked main roads, isolating La Paz from the rest of the country.

Trade unions, including the Regional Trade Union and the Bolivian Central Trade Union, and farmer, indigenous and student organizations participated in the demonstrations.

Demonstrators also demanded the resignation of President Mesa, the closing of the congress and the trial of ex-president Gonzalo Sanchez de Lozada, who resigned in October 2003.

Security was beefed up on Murillo Square as legislators convened on Tuesday for their first session after a week-long recession.

The congress aims to address issues such as the modification of the recently enacted Hydrocarbons Law, the call for a Constitutional Assembly and a bill that would decide how greater autonomy would be granted to Bolivia's regions.

(Xinhua News Agency June 1, 2005)