WASHINGTON (AFP) - US President Barack Obama and Secretary of State John Kerry paid heartfelt tribute to Saudi Arabia's Prince Saud al-Faisal, saying he had left a legacy that would live on despite his death on Thursday.

Prince Saud was one of the highest profile members of Saudi Arabia's ruling elite and formerly the world's longest-serving foreign minister, overseeing four decades of turbulent diplomacy for the oil-rich kingdom.

Obama described him as a "committed and accomplished diplomat."

"Generations of American leaders and diplomats benefited from Prince Saud's thoughtful perspective, charisma and poise, and diplomatic skill," he said in a statement.

"He was committed to the importance of the US-Saudi relationship and the pursuit of stability and security in the Middle East and beyond, and his legacy will be remembered around the world."

Kerry called Prince Saud "a man of vast experience, personal warmth, great dignity and keen insights who served his country loyally and well."

"The longevity of his term in office - he served with 13 US secretaries of state - is a sign of the universal respect with which he was viewed," Kerry said in separate statement from Obama.

"I personally admired him greatly, valued his friendship and appreciated his wise counsel. His legacy as a statesman and diplomat will not be forgotten."

A statement from the Royal Court said Prince Saud, who was born in 1940, died in the United States.