Saudi Arabia's Crown Prince Nayef bin Abdul Aziz Al Saud has died "outside the kingdom", state media say.
Prince Nayef, who was also deputy prime minister and interior minister, had left the country for a holiday and medical tests late last month.
On 3 June, the deputy interior minister said the prince, who was 77 or 78, was in good health and would return "soon".
He was named crown prince in October 2011 after the death of the previous crown prince, Sultan bin Abdul Aziz.
The succession in Saudi Arabia still passes among the sons of former King Abdul Aziz ibn Saud, who established the modern kingdom during his reign from 1932 to 1953.
Next in line is expected to be Crown Prince Nayef's younger brother, Prince Salman, who is the governor of Riyadh.