HAVANA (AP) — The Rev. Lucius Walker, who led an annual pilgrimage of U.S. aid volunteers to Cuba in defiance of Washington's nearly half-century-old trade embargo, has died of a heart attack in New York. He was 80.

Walker, who died Tuesday, headed the nonprofit Pastors for Peace, which since 1992 has brought tons of supplies to Cuba via Mexico and Canada — everything from walkers and wheelchairs to computer monitors and clothing.

A statement on the New York City-based group's website expressed "immeasurable sadness" about "the passing of our beloved, heroic, prophetic leader, Rev. Lucius Walker Jr."

Walker led 21 relief trips to Cuba, the last of which was in July. Pastors for Peace violates the embargo by refusing to apply for permission to export to Cuba, instead traveling through third countries to deliver supplies donated by people in the U.S.

The organization is one of several that bring goods to Cuba in open defiance of the embargo, which took its current form in February 1962. Most are allowed to leave and return to the U.S. without incident, though some past participants have received letters threatening fines and other sanctions from the U.S. Treasury Department.

Walker was born Aug. 3, 1930, in Roselle, New Jersey. He graduated from Shaw University in Raleigh, North Carolina, in 1954, and earned a master of divinity degree from Andover Newton Theological School four years later.

In addition to organizing supply missions, Walker was founding director of the Interreligious Foundation for Community Organization and negotiated an agreement with Cuban officials whereby dozens of American youngsters from poor areas can come to Cuba to study at Havana's Latin American School of Medicine.

As part of that program, American graduates are expected to return to the U.S., earn medical licenses and provide care in underserved communities.

Word of Walker's death was posted on the Cuban government website Cubadebate — where Fidel Castro publishes his frequent opinion columns — and carried on state-controlled television and radio and in newspapers.

The Communist Party daily Granma wrote, "Cubans, in gratitude, have to say that we don't want to think of a world without Lucius Walker."

Pastors for Peace said funeral arrangements had not immediately been made.