Adolfo Calero, who led the largest force of U.S.-backed rebels against Nicaragua’s Sandinista government in the 1980s and found himself entangled in the Iran-contra scandal, died June 2 in the Nicaraguan capital of Managua. He was 80.

The cause was lung ailments, his aide Julio Romero said.

As the leader of the Nicaraguan Democratic Force, Mr. Calero helped pressure the Marxist Sandinistas toward the elections that pushed them from power in 1990.

He also was the key contact with senior U.S. officials during the Iran-contra affair, when officials in President Ronald Reagan’s administration secretly arranged the sale of weapons to Iran to finance the Central American rebels, bypassing congressional restrictions.

Mr. Calero attended the University of Notre Dame in Indiana and told a U.S. congressional committee in 1987 that the experience awakened him to the value of freedom.

He said he returned home in the mid-1950s as “a knight in democratic armor” opposing first the right-wing Somoza dictatorship that ruled Nicaragua for 43 years and later the leftist Sandinistas, who ousted the Somozas in 1979 with broad public support.

“When Somoza was driven from our country, we had a right to expect that our dreams of democracy would be fulfilled. Instead, we got the Soviet totalitarian regime, an oppressive dictatorship operated by the Soviet Union and its proxy, Cuba,” he said.

When the Sandinistas pulled the government sharply left, Mr. Calero, who had headed the local Coca-Cola bottling company, went into exile in Florida.

By 1983, he emerged as the political head of the Nicaraguan Democratic Force, the largest of the contra groups, organized with U.S. aid. It claimed to have 22,000 men under arms at its height.

The conflict killed thousands and added to economic chaos in the country. It eventually led to international mediation, and the Sandinistas agreed to accept free elections if the contras demobilized. The resulting vote removed the Sandinistas from power in 1990. Another election returned Sandinista leader Daniel Ortega to the presidency in 2007.

Mr. Calero denied knowing that any funds donated to the rebels had come from the Iranian weapons sales but acknowledged in 1987 that three former U.S. military officers had helped them buy more than $18 million in military equipment at a time when direct U.S. arms aid was suspended. Another $14 million in donations were used to buy food, clothing and other supplies, he said.

Some of that money was turned into travelers checks, and he told congressional investigators that he had given then-White House aide Oliver North about $90,000 of that to help in the liberation of U.S. hostages in Lebanon.

“I used to tell Col. North, frankly, everything. I had no reservation. I had full confidence and trust in him,” Mr. Calero testified.

After the Sandinistas left power, Mr. Calero returned to Nicaragua, recovering the home the leftist rulers had confiscated from him, and practiced law.

As he was buried Sunday in Managua, relatives showed a photograph of Mr. Calero with Reagan, who had signed it: “For Adolfo Calero. Our fight for justice and democracy in Nicaragua will prevail.”

Survivors include his wife, Maria Ernestina Lacayo de Calero; a daughter; and three grandchildren.

— Associated Press