The gas-rich province of Tarija has become the fourth region in Bolivia to vote for greater autonomy from the central government.

Exit polls on Sunday indicated that about 80 per cent of voters in the southern province had chosen greater autonomy, in a fresh blow to the social reforms plans of the president, Evo Morales.

Of the province's 173,000 registered voters 19.7 per cent chose to remain under the Morales government, ATB television reported based on estimated figures.

Mario Cossio, the mayor of Tarija, said "this day will mark a new page in our national history" that would clear the way for a "better future".

But Morales has said he will not recognise the results of the Tarija vote which he branded as illegal and a waste of resources.

Wealth-distribution agenda

Morales has been pushing his wealth-distribution agenda, saying it will benefit the poorer, mostly indigenous Bolivians of the mountainous western regions. 

Tarija has joined Santa Cruz, Beni and Pando in voting for autonomy

Tarija has only 400,000 inhabitants but has 85 per cent of the country's natural gas, which accounts for 13 per cent of Bolivia's gross domestic product.

The president cancelled a visit to Tarija last week "for security reasons", officials said, and on Saturday, a dynamite explosion damaged a television station in Yacuiba, home to strong opposition to the referendum.

And on Sunday pro- and anti-Morales demonstrators set up competing barricades hundreds of metres from each other in Tarija city, blocking the main road north to Potosi and the capital La Paz.

The referendum also recorded high abstention rates in townships where pro-government, anti-autonomy sentiments were strong.

Political dialogue has collapsed between the Morales-led central government and the opposition, led by the Podemos party and the pro-autonomy governors.

Three other provinces – Santa Cruz, Beni and Pando – are also resisting Morales's policies to redistribute land and resources.