Washington, Jun 17 (IANS): US President Barack Obama Saturday mourned the death of Crown Prince of Saudi Arabia Nayef bin Abdulaziz Al Saud, speaking highly of the prince's role in building security in his country as well as in the region.

"It was with great regret that I learned of the passing of Crown Prince Nayef bin Abdulaziz Al Saud," the president said in a written statement.

"For decades, Crown Prince Nayef served as minister of the interior and 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," Obama said.

The president offered his "deepest condolences" to King Abdullah, the royal family and the people of Saudi Arabia, Xinhua reported.

Nayef, who had been ill for a long time and received medical treatment in Switzerland, died in Geneva Saturday at the age of 78.