Police used tear gas to break up protests at Tarija airport
The leaders of Venezuela and Argentina have cancelled a planned meeting with Bolivia's president after violent clashes between police and protestors.
Presidents Hugo Chavez and Cristina Fernandez had been due to fly to Bolivia to discuss energy contracts.
They cancelled the visit when protestors attempted to storm the runway at Tarija airport in the south.
Tensions are high in Bolivia ahead of a referendum on whether President Evo Morales should remain in office.
Mr Chavez, who is on a visit to Argentina, said calling off the meeting had been the best option in the circumstances.
Elsewhere, two miners died in clashes with police near Bolivia's largest tin mine, near Huanuni, where miners are demanding higher pensions.
In Tarija, police used tear gas to break up dozens of protesters at the airport, shouting slogans against Mr Chavez, who had been scheduled to land there with Ms Fernandez.
The military shut the airport after the protest.
Mr Chavez is a major ally of Mr Morales, and has pledged investment in Bolivia's rich natural gas fields.
Argentina, which buys natural gas from Bolivia, had planned to sign energy accords in the Tarija meeting.
Mr Morales will hold a recall referendum on 10 August, on whether he and eight regional governors should remain in office.
He is locked in a bitter dispute with regional governors who want more autonomy from the central government.
In June the province of Tarija became the fourth region to vote in favour of greater independence.
The government said that both the Huanuni and the Tarija protests were attempts by the opposition to weaken the president before the recall vote.
At the heart of Bolivia's political impasse is Mr Morales's attempt to push through constitutional changes that would enshrine reforms such as land redistribution to Bolivia's indigenous majority and the sharing of wealth with the poorer western regions.
The proposals also include allowing the president to stand for re-election for another five-year term.