According to reports from the capital La Paz, Mesa said late Monday that he would submit his resignation to the congress, reports Xinhua.

"It is my responsibility to say that this is as far as it can go," Mesa said on national television. "I have taken the decision to present my resignation from the presidency."

Mesa's decision came hours after tens of thousands of Indians, miners and labour protesters paralysed La Paz in their largest anti-government march in weeks pressing for their demands.

Protesters marched through La Paz waving banners that read "Nationalise Now" and "The People Demand Nationalisation", and vowed to maintain roadblocks which have caused gas and food shortages in the capital after more than two weeks of blockades.

The recent unrest began after the congress passed a law May 17 to levy a 50-percent tax on foreign oil and gas companies operating in the country, which has the second-largest gas reserves in South America after Venezuela.

If the social chaos and insecurity continue, "without a doubt it is very difficult that the president and the government can continue," said Minister of Presidency Jose Antonio Galindo. "We are on the verge of collapse."

Church leaders had called for a truce to help negotiate a solution to the stalemate. They held a second day of talks Monday as some members of the congress suggested early general elections as the best way out for Mesa.

Earlier Monday, the embattled president managed to flee his office after protesters threatened to storm the presidential palace.

Demonstrations have escalated into riots since May 24 when demonstrators blocked a downtown square in La Paz, where the executive and legislative branches are located, and smashed windows in buildings and cars in the surrounding streets.

The long-term crisis over the gas issue already forced Mesa's predecessor, Gonzalo Sanchez de Lozada, to step down 20 months ago.