Bahrain’s Prime Minister Prince Khalifa bin Salman has died, the Royal Palace announced on Wednesday. “The Royal Court mourns His Royal Highness Prince Khalifa bin Salman, the Prime Minister, who passed away this morning at the Mayo Clinic, US,” the state-run Bahrain News Agency reported. The statement did not indicate the treatment Prince Khalifa, 84, had been undergoing. “The burial ceremony will take place after the arrival of his body, and will be limited to a specific number of relatives,” the court said. King Hamad bin Isa announced a week of mourning with flags flown at half-staff and the closure of government departments for three days from Thursday. Prince Khalifa had served the country as Prime Minister since a year before independence in 1971, making him the longest-serving head of government in the world. The Mayo Clinic has a long history of treating high-ranking Gulf officials, including Sheikh Sabah of Kuwait, who died at the Rochdale hospital on September 29 at the age of 91. The Khalifa family has ruled Bahrain for more than two centuries and Prince Khalifa was the son of former ruler Sheikh Salman bin Hamad, who led from 1942 to 1961. The prince learnt governance at his father’s side as the island remained a British protectorate. He was also the paternal uncle of King Hamad. Alongside his brother Sheikh Isa bin Salman, who took power in 1961 and served as monarch when the nation gained its independence from Britain in 1971, Prince Khalifa helped to forge a modern Bahrain. Under an informal arrangement, Sheikh Isa handled the island’s diplomacy and ceremonial duties while Prince Khalifa ran the government and economy. In the years that followed independence, Bahrain developed rapidly as it sought to move beyond its dependence on its small oil reserves. At that time, Manama was a regional financial, service and tourism centre. The opening of the King Fahd Causeway in 1986 gave Bahrain its first land link with Saudi Arabia. Prince Khalifa was regarded as representing a more traditionalist idea of rule. His involvement in front-line politics waned as he developed health problems, being admitted to hospital in November 2015 but later released. He also travelled to South-East Asia for medical appointments. In late November 2019, he travelled to Germany for undisclosed medical treatments, remaining there for several months. Prince Khalifa was married and has three surviving children, sons Ali and Salman and daughter Lulwa. Another son, Mohammed, died. Sheikh Mohammed bin Rashid, Vice President and Ruler of Dubai, mourned Bahrain's loss. "Our condolences to our brother, the King of Bahrain... and to our beloved Bahraini people on the death of Prince Khalifa bin Salman ... who served his country for a very long time and witnessed its developmental journey that contributed to shaping Bahrain's modern history," Sheikh Mohammed said. Sheikh Mohamed bin Zayed, Crown Prince and Deputy Commander of the UAE Armed Forces, paid tribute to Prince Khalifa on Twitter, calling him one of the "architects of modern Bahrain". The UAE's Minister of State for Foreign Affairs, Dr Anwar Gargash, described Prince Khalifa as a "man of solid principles and attitudes". "The late, great Prince Khalifa bin Salman Al Khalifa is a historical stature whose name was associated with the modern development of Bahrain and the Arabian Gulf," Dr Gargash tweeted. "He is a man of solid principles and attitudes. And a model of the historical men who contributed to crystallising the modern Gulf."