A senior leader of neighboring Colombia's main rebel group was arrested in Ecuador (search), the nation's police chief said Saturday, announcing the capture of the highest-ranking official of the leftist guerrilla army during nearly four decades of war.

A Colombian official said the United States played a role in the capture.

Ecuadorean Police Chief Jorge Poveda confirmed that Simon Trinidad (search) was detained late Friday. He did not give any details about what Trinidad was doing in Ecuador or how long he had been there.

Trinidad is a member of the general staff of the 16,000-member Revolutionary Armed Forces of Colombia (search), or FARC, the largest rebel group in Colombia. He was one of the top negotiators during peace talks with the government that began in January 1999. The talks collapsed in February 2002, and the army resumed operations against the FARC.

"Long live the FARC!" Trinidad shouted while being escorted under heavy police guard to an army helicopter that left for Tulcan, a city on the Colombian border.

Ecuador and Colombian authorities gave differing accounts of how Trinidad was captured.

Poveda said Trinidad was detained during a routine document check in Quito.

But Colombian authorities said Ecuadorean police captured him at a medical clinic after Colombian agents notified them that Trinidad was there seeking treatment.

A Colombian military source said Colombian intelligence had information that Trinidad was suffering from prostate cancer and went to Quito for treatment. Eight agents tracked him down to a medical clinic and notified Ecuadorean authorities, the source said on condition of anonymity.

It was not known where the clinic was located.

Colombian President Alvaro Uribe (search) praised the capture as evidence the country's four-decade leftist insurgency can be defeated.

"Countrymen: The capture of a FARC leader shows that terrorism will never triumph," Uribe told reporters.

He also urged the group's fighters to desert en masse.

"It would be good if all of you left the guerrillas, which only serve to kidnap, murder and sustain a drug empire that only enriches its leaders," he said.

Colombia Defense Minister Jorge Alberto Uribe said the United States played a part in Trinidad's capture, but declined to give details.

A spokesman for the U.S. Embassy in Bogota, Colombia, declined to comment. The United States has been training Colombian forces and supplying intelligence equipment.

"It's the biggest blow the government has dealt the FARC since the organization was born 40 years ago," said Alfredo Rangel, director of the Security and Democracy Foundation, a Bogota think tank.

The FARC likely will be looking to strike back, he said.

Colombia had issued an international arrest warrant to Interpol, the international police agency, and offered a reward for Trinidad's arrest.

The capture comes after the commander of the Colombian army, Gen. Martin Orlando Carreno, made it his New Year's resolution to capture or kill at least one of the seven secretariat members within a year, or resign.

Ecuadorean President Lucio Gutierrez said he informed a jubilant President Uribe about the capture and Trinidad's imminent extradition to Colombia.

"I think this really helps maintain excellent relations between our two countries and improves regional security," Gutierrez told Colombia's RCN radio.

The 54-year-old rebel, whose real name is Ricardo Ovidio Palmera Pineda, is wanted on some 30 counts of massacres, bombings and kidnappings.

The Colombian government had multimillion-dollar bounties on members of the FARC secretariat, but it was unclear how much money was offered for Trinidad.

His capture is a boost to President Uribe, who faces growing pressure to show concrete successes to justify the tax hikes and spending cuts he has used to pay for the war.

Trinidad is an oddity amid the mostly peasant ranks of the FARC. He is the son of a wealthy cattle rancher who studied economics and went on to be a banker before becoming a rebel.

He once said the growing gap between the rich and poor in Colombia drove him to take up arms in the late 1980s, before becoming one of the FARC's most visible faces.

Earlier this month, the FARC reported that another member of the secretariat, Efrain Guzman, died of natural causes at 68. Guzman, who was replaced by Ivan Rios, was one of the FARC's founding fathers but was the least well-known of the top commanders.

The FARC and a smaller rebel group, the National Liberation Army, have been battling to topple the government and establish a Marxist state in Colombia for 39 years.