LA PAZ, Bolivia President Evo Morales on Saturday accused an opposition governor of using foreign thugs against government supporters in violence that has claimed at least 18 lives and prompted him to declare martial law in a breakaway province.
In a bid to defuse the bitter dispute over a new constitution and land reform that threatens to tear apart the poor Andean nation, Chile called for an emergency meeting of South American leaders for Monday.
"A larger tragedy has to be avoided," said Venezuelan President Hugo Chavez, a strong ally of Bolivia's leftist president, confirming he would attend the meeting.
Morales described as an ambush a gunbattle in the eastern province of Pando on Thursday that led him to impose martial law the next day. "These people were massacred," he told a news conference on Saturday.
Interior Minister Alfredo Rada said 16 people were killed in the clash the majority peasants who back Morales and authorities said another two people died Friday at Pando's main airfield as government troops took control, opening fire to disperse protesters.
Bolivia's first indigenous president said he would not hesitate to extend the state of siege if necessary to the other three pro-autonomy provinces in eastern Bolivia where separatists seized government offices and natural gas fields last week in the gravest crisis of his nearly 3-year-old presidency.
Government opponents are demanding Morales cancel a Dec. 7 referendum on a new constitution that would help him centralize power, run for a second consecutive term and transfer fallow terrain to landless peasants.
The emergency summit in Chile comes after both Morales and Chavez expelled the U.S. ambassadors to protest what they say is Washington's inciting of anti-government protesters in Bolivia.
U.S. officials call the accusations baseless.
At Saturday's news conference, Morales said "Brazilian and Peruvian assassins under the command of the governor of Pando" took part in what he said was an ambush of government supporters.
Pando and the rest of the country were reported quiet on Saturday, though Interior Ministry officials told The Associated Press that they expected more bodies to turn up from Thursday's violence, which occurred some 30 kilometers (20 miles) from the provincial capital of Cobija.
The governor, Leonel Fernandez, denied any responsibility.
"The government has a great ability to distort things and its arguments already the same, accuse without reason," Fernandez told Radio Fides.
The state of siege prohibits people from gathering or carrying weapons. It was declared hours after Morales and opposition governors from the four eastern provinces agreed to talks on ending the crisis.
"We all agree that we have to look for a point of compromise," said Carlos Dabdoub, secretary for autonomy in Santa Cruz Bolivia's richest and the center of anti-Morales opposition.
Tarija Gov. Mario Cossio announced he would travel to La Paz for negotiations.
The protests temporarily disrupted natural gas exports to Brazil Bolivia's No. 1 customer.
Associated Press writers Frank Bajak in Bogota, Colombia, Ian James in Caracas, Venezuela, and Eduardo Gallardo in Santiago, Chile contributed to this report.