Demonstrators have fought pitched battles with police and troops

Gonzalo Sanchez de Lozada shelved plans to export gas to new markets, bowing to a key demand of the protesters.

He said his government would consult the opposition before taking a final decision and the plans were suspended until 31 December.

But he insisted the protests were part of a foreign plot to subvert his rule.

At least 10 more people died in clashes with police on Monday in and around La Paz and nearby El Alto, according to Sacha Llorenti, vice-president of Bolivia's Permanent Human Rights Assembly.

The death toll has risen to more than 45 since the protests erupted nearly five weeks ago.

At least 12 people were reportedly killed when a petrol station they were trying to set ablaze exploded.

Economic woes

A BBC correspondent in the region says the civil unrest is fuelled by wider issues than the gas project. Peasant farmers want land reform, the elderly want better pensions and workers want more money.

Impoverished Bolivians fear they will see little benefit from gas sales

The ethnic Indian leaders of the protests, Felipe Quispe and Evo Morales, quickly rejected the offer of talks on the gas plan and demanded the president's resignation.

Media reports said police in El Alto battled protesters until their tear gas and rubber bullets ran out.

Thousands more demonstrators thronged the streets of La Paz, Cochabamba, Oruro and Potosi on Monday.

BBC News Online's Latin America analyst, Robert Plummer, says it has long been an article of faith among Latin American economic nationalists that a country must retain control over natural resources such as gas at all costs.

The Bolivian president's free-market reform strategy, centring on good relations with the United States, has bred particular resentment.

President sees plot

But in a national broadcast he insisted that "a large subversive project, organised and financed from abroad, is looming to destroy Bolivian democracy".

The dramatic incidents that have brought grief to the Bolivian family have exposed the insoluble differences between our visions Jorge Torres Oblea

He would not resign, he added, because it was his constitutional duty to uphold the democratic decision of the voters who had elected him.

The United States backed President Sanchez de Lozada, saying it would not support any regime that resulted from undemocratic means.

But Bolivian Vice-President Carlos Mesa announced he was withdrawing his support for the president's policies and the Minister of Economic Development, Jorge Torres Oblea, tendered his resignation.

La Paz is suffering food and fuel shortages because of the roadblocks and strikes, while all flights to and from the airport have been suspended.

Vice-President Mesa said there was no justification for the deaths and the government was not offering the opposition "enough".

Economic Development Minister Torres Oblea said his differences with the president were "insoluble".

Nationalisation

Peasant farmers began their self-proclaimed "war for gas" almost a month ago as protesters expressed fears that proceeds from the gas would simply enrich foreign companies investing in the project.

They say they do not trust the government to spend the revenues wisely and fear that much of the money will be lost to corruption.

Protesters are calling on the government to nationalise the country's natural gas resources, saying they should be processed in Bolivia to make higher value products.