Colombia's president said his cross-border raid on rebels was justified because Ecuador woudn't expel the guerrillas from its territory, even as Nicaragua broke off diplomatic relations Thursday and Venezuela threatened to slash trade and nationalize Colombian businesses.

Latin American foreign ministers searched for a peaceful way out of the region's worst diplomatic crisis in years during a meeting in the Dominican Republic, and the presidents of Colombia, Venezuela, Ecuador and at least nine other nations were flying in to join them.

Colombian President Alvaro Uribe met for three hours Wednesday night with directors of news media, in an off-the-record talk that his office authorized for publication on Thursday. He expressed frustration at what he called inaction by Ecuador over Colombian guerrilla camps in its territory.

"What does one do when bandits are shooting from the other side and the government doesn't do anything?" Uribe asked. "It's my job to defend 43 million Colombians."

Ecuadorean President Rafael Correa has said his troops have "captured" dozens of rebel camps, but Colombian officials say the rebels were always tipped off. Uribe said he couldn't give Correa advance notice of the raid because "I was sure that the operation would have failed."

He said Saturday's raid, which killed 24 people, was the sixth since his 2002 election against Raul Reyes, a top leader of the Revolutionary Armed Forces of Colombia, or FARC. Ecuador was investigating whether five Mexicans visiting for a leftist conference were among them, an official said on condition of anonymity because he was not authorized to speak with news media.

Uribe refused to rule out another such incursion into Ecuador or Venezuela, saying he first needs assurances from Correa and Venezuelan President Hugo Chavez that they are not harboring rebels.

But he said he didn't want war with any of his neighbors -- that the thought "doesn't even cross our minds." Venezuela and Ecuador have each sent thousands of soldiers to their borders with Colombia, but Uribe said he won't mobilize troops.

Nicaragua broke off relations Thursday with Colombia over the incident. President Daniel Ortega is a strong ally of Chavez and Correa, and Nicaragua has a long-standing maritime boundary dispute with Colombia.

"We are breaking off relations because of the political terrorism being carried out by the government of Alvaro Uribe, not because of the Colombian people," Ortega said during a visit from Correa.

Chavez said he would squeeze his country's US$6 billion (euro4 billion) annual trade with Colombia, saying: "We aren't interested in Colombian investments here." He added: "Of the Colombian businesses that are here in Venezuela, we could nationalize some."

That could create economic havoc, especially in Venezuela, which is already plagued by shortages of basic foods from milk to chicken. Chavez said Venezuelans can no longer depend on Colombia, "not even for a grain of rice." Colombia's finance minister said a cutoff could cost his country 100,000 jobs.

Chavez and Correa welcomed a resolution by the Organization of American States on Wednesday that calls the raid a violation of Ecuador's sovereignty. But they demanded an explicit international condemnation.

In the Dominican capital of Santo Domingo, foreign ministers of the 20-nation Rio Group searched for a "peaceful, negotiated solution," Bolivia's foreign minister said. Presidents are to face off there Friday.

"I do hope there will be a diplomatic outcome to this," U.S. Secretary of State Condoleezza Rice said in Belgium. She added that she hoped to win support from the leaders of Brazil and Chile when she travels to South America next week.

Colombia contends documents in a laptop belonging to Reyes indicate close rebel ties to Correa and Chavez. Correa counters that Reyes' slaying stymied the imminent release of 12 FARC-held hostages that he claims his government was negotiating.

Chavez, who has helped free six hostages this year, said Thursday his efforts won't stop.

"In spite of everything, and no matter what happens, we will continue struggling ... for the liberation of all the hostages in the hands of the FARC, for the liberation of our much-loved Ingrid Betancourt," Chavez said, referring to the French-Colombian politician held for six years.

President Nicolas Sarkozy of France appealed for her release in an interview on Colombian television, calling Betancourt's freedom "a personal commitment" for him and "a national cause" for France.

Meanwhile, some 40,000 people took part in a Bogota march for victims of Colombia's long-running conflict that had a decidedly anti-Uribe flavor. Many criticized the president's no-holds-barred military campaign and the right-wing paramilitaries formed to counter the guerrillas.

"Uribe is the one who has always wanted war -- and the United States, too," said 53-year-old marcher Jorge Sanchez.

Smaller marches were held elsewhere around the world.

An anti-guerrilla march organized on Facebook and supported by Uribe drew millions last month.