US President Barack Obama said Crown Prince Nayef, who had been next in line to rule Saudi Arabia, the world's top oil exporter, had for decades "dedicated himself to the security of Saudi Arabia as well as security throughout the region."
Under his leadership, the United States and Saudi Arabia developed a strong and effective partnership in the fight against terrorism, one that has saved countless American and Saudi lives. On behalf of the American people, I would like to offer my deepest condolences to King Abdullah, the royal family, and the people of Saudi Arabia.
Seen as a key ally for the West, Saudi Arabia has provided critical intelligence to foil al Qaeda plots, bankrolled pro-Western Arab governments and has supported Washington's attempts to isolate Iran.
More top news
A cruise ship had to abandon its voyage to the Bahamas after being caught up in hurricane-like conditions off the US coast at the weekend.
A cold and perhaps frosty start, with a risk of wintry showers in the south west. Sunny spells and showers for the rest of today.
Experts have called for the "potentially dangerous" practice of sending mentally ill people long distances for treatment to end.