LA PAZ, April 17 (Reuters) - Bolivian protesters stormed a facility that controls exports of natural gas to Argentina on Tuesday after clashing with security forces in the southeastern Chaco province.

Police and military fired tear gas and rubber bullets at protesters, leaving several injured, while demonstrators fought back with stones and sticks, radio Erbol reported.

It was not clear whether the protest forced a cut in exports.

The protest was partially triggered by competing claims by the districts of Gran Chaco and O'Connor, in the Tarija province, to rights over the large Margarita natural gas field, which is operated by Spain's Repsol-YPF.

The field is expected to generate millions of dollars in state revenue in the coming years.

Tarija Gov. Mario Cossio is set to rule which of the two districts will have the right to 45 percent of the approximately $100 million in annual taxes that could come from future exports of Margarita's reserves to Argentina.

Political and civic leaders in Gran Chaco had threatened to occupy fields or take over pipeline control stations to cut exports.

Repsol-YPF <REP.MC>, Brazil's Petrobras <PETR4.SA> and France's Total <TOTF.PA> operate different natural gas fields in Tarija, where 80 percent of Bolivia's natural gas reserves lie.

Bolivia put natural gas fields and pipelines in the region under military control on Monday to deter potential protests that could affect exports to Brazil and Argentina.

Protests began last week in Gran Chaco with hunger strikes by lawmakers and city officials, and took force on Monday with road blockades, including border crossings to Argentina and Paraguay.

On Tuesday, protesters refused to meet with a government envoy that traveled some 750 miles (1,200 km) by land from the country's administrative capital La Paz to negotiate with them.

Bolivia nationalized its energy industry a year ago, forcing foreign operators to pay much higher taxes and making the government the owner of energy reserves.

The government expects Bolivia's 30 million cubic meters a day of natural gas exports to Argentina and Brazil to reach an annual value of $2 billion this year.

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