Lieutenant Colonel Julio Cesar Galindo, part of a group calling itself the ‘Generational Military Movement’, appeared on privately run television telling President Mesa to “leave, simply quit the presidency and make room for the government of the people.”
A second officer, Lieutenant Colonel Julio Herrera, added: “This is not a military coup d’etat, but a declaration of the people.”
Armed forces chief, Admiral Luis Aranda dismissed the broadcast as “an isolated incident”, saying the statement did not “represent the opinion of the services of the armed forces which stand firm in the defence of the rule of law, democracy and the country’s institutions.”
But the pressure on President Mesa continues to mount, as thousands of angry miners, indigenous Bolivians and farmers took to the streets of La Paz demanding the nationalisation of the nation’s oil and gas industry.
Some demonstrators were seen brandishing whips and forcing street vendors and merchants to shut down their businesses.
Despite a heavy police presence in the centre of the city, some protesters were able to hurl three sticks of dynamite at a building near the Bolivian Congress.
No injuries were reported, but there was some structural damage, La Paz police chief Hernan Jaimes told the Agence France Presse news service.
Opposition groups have accused the government of failing to stand up to multinational energy companies and ensure higher returns from the country’s rich natural gas reserves.
Last week, Bolivia’s Congress voted to give the state a bigger stake in the energy industry.
But activists are far from satisfied with the result, and neither are business interests.
According to the Bloomberg news agency, Bolivian Hydrocarbon Chamber president Raul Kieffer said several gas fields would become unprofitable if hit with the 50 percent tax rate proposed by the new law.
Deep-seated dissent fuelled similar protests 19 months ago and saw Carlos Mesa, then vice-president, take over from his predecessor President Gonzalo Sanchez de Lozada.
As protests enter their fourth day, food and fuel are reportedly beginning to run out in the capital which has become virtually cut-off from the rest of the country by a series of road blocks.