Nawaf Al-Faisal, a relative, announced the death on Facebook, while a ministry spokesman also confirmed the death on Twitter and expressed condolences.
I wish I could deny the rumor of the news of your death," the spokesman Osama Nugali tweeted.
Prince Saud's nephew Saud Mohammed Al-Abdullah Al-Faisal also acknowledged the death. "May God accept him in paradise," he wrote on Twitter.
Prince Saud, who was appointed in 1975, was the world’s longest serving foreign minister.
The prince, who was born in 1940, was one of the highest profile members of Saudi's ruling elite and steered the diplomacy of the world's leading oil exporter for four decades before stepping down in April for health reasons.
Prince Saud retained an influential position in Saudi foreign policy circles even after his replacement, serving as an official adviser to King Salman, who took power in January, and was sometimes present when foreign leaders met the monarch
Prince Saud's tenure covered Israeli invasions of Lebanon in 1978, 1982 and 2006, the Palestinian intifadas that erupted in 1987 and 2000, Iraq's invasion of Iran in 1980 and Kuwait in 1990, and a US-led coalition's occupation of Iraq in 2003.