By JUAN FORERO
 
LAS MERCEDES DE TASAJERA, Venezuela, Jan. 18 - Rodrigo Granda is a leading operative in Colombia's oldest rebel group, a man who for years roamed the world drumming up support for his organization, with Colombia's government in hot pursuit.

Yet, for two years before his capture last month in Caracas, Venezuela's capital, he lived comfortably in a two-story house in this picturesque mountain community that is a weekend retreat for Venezuelan Army generals, Caracas businessmen and well-off retirees. He came and went freely, ordering construction supplies for his home and frolicking in his pool while still serving as the "foreign minister" for the Revolutionary Armed Forces of Colombia, the authorities in Bogotá, Colombia, say. In fact, he had enjoyed the privileges of Venezuelan citizenship and had voted in a recent election.

The revelations about Mr. Granda's apparently breezy day-to-day life in Venezuela and the murky operation that led to his capture in Caracas have led to the most serious diplomatic crisis between neighbors who are ideological opposites: the leftist Venezuelan government of President Hugo Chávez and the conservative Colombian administration of President Álvaro Uribe.

The dispute has drawn in the Bush administration, which on Jan. 15 vocally threw its support behind Mr. Uribe, Washington's closest ally in Latin America. Then on Tuesday in her Senate confirmation hearing, Condoleezza Rice, the secretary of state-designate, said that Venezuela's government had been a "negative" force in the region while stifling the opposition at home.

"We are very concerned about a democratically elected leader who governs in an illiberal way, and some of the steps he's taken against the media, against the opposition, I think are really very deeply troubling," Ms. Rice said at the hearing.

The comments drew an angry rebuke from Mr. Chávez's government, which in August won a landslide election that reinforced the president's mandate. The Bush administration's strident opposition has appeared to end any chance that the United States could play a role in resolving this or any other crisis involving Mr. Chávez's government.

[This week Brazil demonstrated its growing diplomatic assertiveness after announcing that its left-leaning president, Luiz Inácio Lula da Silva, who is close to Mr. Uribe and Mr. Chávez, would mediate the crisis.]

Mr. Chávez's government accused Colombia of having bribed a group of Venezuelan National Guardsmen to arrest Mr. Granda on Dec. 13. Saying that Colombia had violated Venezuelan sovereignty, Mr. Chávez recalled his ambassador to Bogotá, suspended bilateral accords and demanded an apology.

Colombia responded defiantly, issuing a presidential bulletin saying it had the right to offer rewards leading to the capture of Colombian rebels, wherever they might hide. Colombia also turned over the names of rebels it says often seek refuge in Venezuela. [On Friday, Venezuela said it would investigate.]

The dispute is not the first between presidents who, while from different ends of the ideological spectrum, are both strong-willed populists with loyal followings in their countries. The two leaders have in fact agreed to increase trade and cooperation on large projects like a pipeline that would transport Venezuelan oil across Colombia to the Pacific.

Yet, Mr. Chávez's government has infuriated Mr. Uribe's government and that of his predecessor, Andrés Pastrana, by overlooking the presence of rebels in Venezuela and, in some cases, helping them, Colombian officials say.

Venezuela has responded by saying it cannot adequately patrol the rugged and sparsely populated 1,400-mile border separating the countries. Colombian rebels, to be sure, operated in Venezuela long before Mr. Chávez won office and are active in the four other countries that border Colombia.

But the Granda case, involving a high-ranking rebel who lived far from the border region, has become the most heated diplomatic squabble between Colombia and Venezuela since the 1980's, one that political analysts say is exacerbated by the fact that the two presidents rarely back down from a fight.

"For Uribe the issue is terrorism, and terrorism trumps everything else," said Michael Shifter, a senior analyst at the Inter-American Dialogue, a Washington policy analysis group that tracks events in the region. "Chávez, obviously, is very sensitive of the sovereignty question. What both leaders have in common is they're extremely proud. Pride often stands in the way of working toward a solution."

Each leader is particularly aggrieved by his counterpart's actions regarding Mr. Granda.

Colombia said it issued an international arrest warrant for Mr. Granda more than a year ago, yet he had been so nonchalant about security that in early December he openly attended two conferences of leftists in Venezuela.

Venezuela says it was never alerted about Mr. Granda and contends that his citizenship papers were fraudulent.

Venezuela has instead focused on Colombia's role in Mr. Granda's capture, saying that Colombia's security services orchestrated what Mr. Chávez calls a kidnapping. Five Venezuelan National Guardsmen have been arrested, accused of having been bribed by the Colombian authorities to make the arrest.

"A crime was committed here, and Venezuela's sovereignty was violated," Mr. Chávez said in a television broadcast last Sunday.

Here in Las Mercedes de Tasajera, about two hours southwest of Caracas, residents, local business owners and yard workers remember Mr. Granda simply as the Colombian, a man who was not averse to meeting and talking to his neighbors but who revealed little about himself.

"He talked to a lot of people," said Daniel López, a retired businessman who has lived here for 30 years. "He was very courteous, very educated, but also quiet about his ways."

Others here wonder if other Colombian guerrillas are in the misty hillside farms.

"If this one was here, there have to be others," said Pedro Brito, 50, who guards one of the weekend homes. "This is a place where people can hide. It is safe. There are some millionaires here. There are colonels and generals. Who would imagine a guerrilla?"