"The Saudi Crown Prince was a strong leader and a good friend to the United States over many years, as well as a tireless champion for his country," U.S. Secretary of State Hillary Clinton said during a visit to Tajikistan, in the first official U.S. comment on his death.

"He will be missed," she said at a news conference.

"Our relationship with Saudi Arabia is strong and enduring and we will look forward to working with the (Saudi) leadership for many years to come," Clinton said.