Bahrain's prime minister, Prince Khalifa bin Salman Al Khalifa, died early Wednesday at the age of 84, the royal palace announced on Twitter.

"The Royal Court mourns His Royal Highness ... who passed away this morning at Mayo Clinic Hospital in the United States," Bahrain's state news agency said.

A burial ceremony is expected to take place upon the repatriation of his body.

The king has ordered a week of national mourning and for flags to be flown at half-mast. Work at government departments will also be suspended for three days starting on Thursday.

In November 2019, Prince Khalifa traveled to Germany for undisclosed medical treatments, but returned to Bahrain several months later.

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Longest-serving prime minister

Prince Khalifa was one of the world's longest-serving heads of government. He held the post of prime minister for almost 50 years, having entered office after Bahrain gained independence from Britain in 1971.

He was born into the Al Khalifa dynasty that has ruled Bahrain for the past two centuries. His father, Sheikh Salman bin Hamad Al Khalifa, ruled the island from 1942 to 1961 until Prince Khalifa's brother took power in 1971. 

Under an informal arrangement, the prince ran the government and economy, while his brother handled the island's diplomacy and ceremonial duties.

Protests over corruption

Prince Khalifa, a staunch ally of the United States and Saudi Arabia, was often seen as a controversial figure. He was deeply unpopular with the Sunni-ruled kingdom's Shiite majority, and his time in office was severely tested by the Shiite-led Arab Spring protests in 2011.

At the height of the protests, thousands of demonstrators besieged the prime minister's office, demanding that the prince step down over long-running allegations of corruption.

The security forces later crushed the protests with help from troops from neighboring Saudi Arabia and the United Arab Emirates.

An earlier version of this article erroneously had a picture of the Crown Prince. This has been corrected.

nm/rt (AFP, Reuters, AP)