Nicaragua broke off diplomatic ties with Colombia on Thursday, widening a Latin American crisis over a raid by Colombia on a rebel camp inside Ecuador last Saturday.

Venezuela and Ecuador have also cut relations with Colombia and poured troops to their frontiers with the U.S.-backed state in reaction to the cross-border raid, which prompted leftist allies in Latin America to line up against Colombia.

Nicaraguan President Daniel Ortega, an ex-guerrilla whose country is in a territorial dispute with Colombia, said he was breaking off relations "in solidarity" with Ecuadorean President Rafael Correa, who was visiting Managua.

Ortega's move strengthened the leftist alliance that has formed around Ecuador and Venezuela and left their neighbor, Colombian President Alvaro Uribe, increasingly isolated and under pressure to apologize.

"We are breaking with the terrorist politics that Alvaro Uribe's government is employing," Ortega said.

With governments worldwide, including the United States and Russia, calling for a negotiated solution, Colombia played down worries that the dispute could escalate into what would be the first military conflict between Latin America nations in more than a decade.

"I don't think there is a risk of war. The Colombian government has been very clear it won't use force," Colombian Vice President Francisco Santos told Reuters during a visit to Brussels for talks with EU officials.

"It won't fall into the game of provocation."

Venezuelan President Hugo Chavez, who says socialism can unite South America against what it calls "U.S. imperialism," jumped into the dispute during the weekend, warning war could break out.

He had been feuding for months with Colombia over his efforts at mediating the release of hostages held by the FARC guerrillas. A FARC leader who was negotiating hostage releases was among those killed in the Colombian cross-border raid.

BUSH-CHAVEZ DIVIDE

The Pentagon said a military conflict is unlikely - and international investors generally agree. Wall Street economists said they expect the crisis to blow over despite the leaders' brinkmanship and risks of military missteps.

But the crisis has exposed divisions across the region.

A self-styled socialist revolutionary and Cuba ally, Chavez is the leader of a left-wing group of Latin American nations who get financial aid from Venezuela, a major oil exporting nation.

Most Latin American countries support Colombia against the Marxist rebels of Revolutionary Armed Forces of Colombia, or FARC. But many, including diplomatic heavyweight Brazil, have also condemned Uribe for the raid and demanded he apologize to Ecuador.

U.S. President George W. Bush has vowed to stand by Uribe, whose country receives billions of dollars in U.S. military aid against guerrillas and drug-traffickers.

The United States helped block moves at the Organization of American States for a formal condemnation of Colombia this week. Instead, the Western Hemisphere's top diplomatic body criticized Colombia for violating Ecuador's sovereignty.

Correa welcomed that diplomatic move on Wednesday but said it did not go far enough.

He hopes to win an explicit condemnation against Colombia in a statement at a summit of Latin American leaders in the Dominican Republic, where he was headed later on Thursday.

"We have to make decisions ... to clearly condemn the Colombian aggression and make sure this government never again dares to attack a brother country," he said.

Uribe will also attend the summit, where he hopes to persuade leaders he had to act against the rebel FARC himself because Ecuador allows the guerrillas to take refuge there. Uribe also accuses Chavez of supporting the FARC, which has fought a decades-long insurgency.

It is not clear if Chavez will also travel to the Dominican Republic. But there is no doubt of his position.

"Never before has any country in Latin America reached the point of taking a preemptive attack doctrine or the doctrine of pursuing your internal enemies in every corner of the globe," he said.