Bolivian President Evo Morales said on Wednesday that he was expelling US ambassador Philip Goldberg for allegedly inciting violent opposition protests.

Morales' announcement came hours after a pipeline blast triggered by saboteurs forced the country to cut natural gas exports to Brazil by 10 per cent.

"I ask our foreign minister that, following the legal and diplomatic guidelines, to send a letter to the (US) ambassador (Philip Goldberg) today letting him know of the national government's and the president's decision that he urgently return to his country," Morales said in a speech at the presidential palace.

"We don't want separatists, divisionist people," Bolivia's leftist president added.

In Washington, US State Department spokesman Gordon Duguid called the accusation "baseless" and said the US government had not yet received a note about the ambassador.

The Bolivian leader did not offer specific evidence against Goldberg, but he has long accused the diplomat of conspiring with Bolivia's conservative opposition.

Anti-Morales protests reached a crescendo on Tuesday with the sacking and burning of government offices in Santa Cruz in which at least 10 people were reported injured.

Anti-government activists also seized several natural gas installations in the east. The government immediately ordered additional troops to Bolivia's rebellious eastern provinces to secure gas and oil installations.

The pipeline blast reduced by 3 million the 30 million cubic meters of gas Bolivia sends Brazil each day, he said. But in Brazil, Mining and Energy Ministry officials said the gas flow remained normal.

Any supply interruption could have serious consequences for Brazil's booming economy. Bolivia supplies its bigger neighbour with 50 per cent of its natural gas, used for power generation and as fuel for cars and cooking.

Morales' opponents in the east are seeking a greater share of revenues from natural gas, Bolivia's chief export, for the richer lowland provinces, home to the bulk of its gas fields.

Morales has devoted much of those revenues to programmes which benefit the poor and elderly. He has called the protests a "civil coup."

Opposition leader Branko Marinkovic, the owner of large land holdings in soy-growing Santa Cruz, said on Tuesday that the only way out of the conflict is for the government to cancel a December 7 referendum on a new constitution.

The proposed new constitution, which would give indigenous groups greater control of their traditional lands and make it easier for the government to redistribute fallow land, was approved by a special assembly last year amid an opposition boycott.