Harry Barnes, a high-ranking U.S. diplomat who as President Ronald Reagan’s ambassador to Chile in the 1980s aggressively promoted democracy there and clashed frequently with the country’s dictatorial president, Gen. Augusto Pinochet, died Aug. 9 in Lebanon, N.H. He was 86.

In a long career, Barnes was ambassador to Romania and India as well as to Chile. During the Carter administration he was director general of the Foreign Service, serving as a policy adviser to Secretary of State Cyrus Vance.

He was best known for his years in Chile. On July 12, 1985, when Barnes presented his credentials to Pinochet, leader of the military coup that overthrew the socialist Salvador Allende in 1973, he offered blunt advice: “The ills of democracy can be cured only with more democracy.”

Even before meeting with Pinochet, Barnes had ignored diplomatic protocol by huddling with opposition leaders and attending a candlelight religious observance by human rights activists. He was carrying out an explicit Reagan initiative: to confront tyranny by the right wing as well as the left.

Pinochet responded by demanding, “Since when are ambassadors arbiters of our internal problems?” He added, “We are not anyone’s colony or slave.”

In July 1986, Barnes attended the funeral of a young man who had been burned in a protest against the government. Barnes and his wife, Elizabeth, were tear-gassed as they awaited the start of the funeral march. The ambassador’s attendance had been approved by the White House and the State Department, but Sen. Jesse Helms, R-N.C., condemned him for “planting the American flag in the midst of Communist activity.”

Some questioned whether Barnes, in attending the funeral, had sacrificed U.S. influence by infuriating Pinochet, who banned Barnes from the presidential palace and ordered photographers to crop him from ceremonial photos. But when Chile had a referendum on Oct. 5, 1988, on whether to replace Pinochet, Barnes helped to ensure a fair vote by financing a parallel vote count and voter education projects.

When the ambassador heard of a plan by right-wing commandos to disguise themselves as police and stage false raids on election night to provoke riots and a coup, he told Washington, Pamela Constable and Arturo Valenzuela wrote in their 1991 book, “A Nation of Enemies: Chile Under Pinochet.” The State Department called in Chile’s ambassador to the U.S. to express its concern.

Nearly 60 percent of the voters chose to have elections to replace the government. Pinochet left the presidency on March 11, 1990, and transferred power to a democratically elected president, Patricio Aylwin.

Barnes graduated summa cum laude from Amherst College and earned a master’s degree in history from Columbia. He entered the Foreign Service in 1950 and, starting in Mumbai, rose through the ranks, going on to serve in Prague, Moscow, Nepal and Romania.

After serving as director general in Washington, he was appointed ambassador to India. As the first career diplomat (as opposed to a political appointee) to hold that post in more than a quarter-century, Barnes helped negotiate nuclear fuel and arms deals.

In 1985, when the Reagan administration was growing frustrated with its inability to influence Pinochet, Secretary of State George P. Shultz selected Barnes. Elliott Abrams, assistant secretary of state for inter-American affairs, called him “a world-class ambassador.”

While ambassador to Chile in 1987, Barnes became embroiled in a controversy over an affair that his wife had with a Romanian chauffeur for the U.S. Embassy in Bucharest in the 1970s. She had admitted the affair to an investigator in 1978, and several federal agencies had found no security breach. Vance, the secretary of state at the time, had ordered the information sealed.

The affair became public when a former high-ranking Romanian intelligence official told reporters about it.

Barnes retired from the Foreign Service in 1988. He went on to teach at several universities and to help plan and carry out the human rights efforts of the Carter Center in Atlanta from 1994 to 2000.