Bolivian president says gun battle was work of `assassins'

A dispute that killed at least 18 was described by Bolivian President Evo Morales as an ambush of his political supporters.

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 on Monday.

''A larger tragedy has to be avoided,'' said Venezuelan President Hugo Chávez, a strong ally of Bolivia's leftist president, confirming he would attend the meeting.

Morales described as an ambush a gun battle 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 Saturday.

Interior Minister Alfredo Rada said 16 people were killed in the clash -- the majority of them peasants who back Morales -- and authorities said another two 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 eastern provinces 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 lands to landless peasants.

The emergency summit in Chile comes after both Morales and Chávez expelled the U.S. ambassadors in their countries to protest what they say is Washington's inciting of opposition protesters in Bolivia.

U.S. officials called the accusations baseless and expelled the Bolivian and Venezuelan ambassadors in Washington.

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 Gov. Leopoldo Fernández denied having anything to do with the violence, saying it was not an ambush but rather an armed clash between rival groups.

Peasant leader Antonio Moreno told The Associated Press in a phone interview that the violence began when he and several truckloads of companions came upon an opposition blockade on a jungle highway.

He said there was some fighting, then suddenly a man exited a vehicle and fired on the farmers with a submachine gun.

Pando and the rest of the country were reported quiet on Saturday.