SAO PAULO -(Dow Jones)- Brazil's government is maintaining its offer to mediate in the conflict threatening to tear up Bolivia.

President Luiz Inacio Lula da Silva's international affairs secretary, Marco Aurelio Garcia, and acting Foreign Minister Samuel Pinheiro Guimaraes are ready to fly to La Paz to lead talks aimed at guiding the neighbor away from civil war, but they will go only at the invitation of Bolivian President Evo Morales, a presidential spokeswoman said Friday.

"We will not tolerate a rupture to the constitutional order in Bolivia," Garcia told journalists late Thursday, making it clear that Lula's government would support Morales.

Protests against a Morales proposal to redirect gas revenues led to violence this week as demonstrators in the country's energy-rich eastern provinces invaded government buildings, set up roadblocks and cut off gas supplies.

Leaders in the eastern provinces have threatened to split from La Paz and declare independence, which could lead to civil war.

Garcia said the offer to mediate is based on Bolivian government affirmations that it is ready to talk with the opposition.

On Thursday, Lula talked to Argentine President Cristina Kirchner and Venezuelan President Hugo Chavez to discuss ways to help resolve the political crisis hitting Bolivia, the spokeswoman said.

The Brazilian government is keen to show its support for Bolivia's democratically elected government, she said.

The Brazilian government continues to monitor the situation and has no comment to make on a threat by Hugo Chavez to intervene militarily if an attempt was made to overthrow Morales, the spokeswoman said.

Beyond geopolitical concerns, Brazil has solid economic reasons to hope the conflict doesn't escalate.

Brazil imports about half its natural-gas needs from its neighbor. This gas comes from regions where protests are strongest.

Protesters disrupted exports of gas this week, blocking two valves on the pipeline system that serves Brazil.

The protests mean supply to Brazil is down 10% from the 31 million cubic meters normally sent each day, and Brazil's governors are nervous that greater disruption may occur.

-By Alastair Stewart, Dow Jones Newswires; 5511 2847-4520; alastair.stewart@ dowjones.com