State-run Bahrain News Agency has reported the death of Prince Khalifa bin Salman al-Khalifa, the leader of the country's government. Prince Khalifa, who served as the country's prime minister for nearly five decades, died at the age of 84 on Wednesday.

The news agency said that Prince Khalifa, who holds the record for being the world's longest-serving prime minister, died at the Mayo Clinic in the U.S. The report did not specify the cause of death but prior reports had revealed that the prime minister had undergone heart surgery after suffering from two separate heart attacks.

Sources with knowledge in the matter said that Prince Khalifa's heath has been on a steady decline over the past few years. He had flown to the U.S. in August with the government claiming that it a "private visit."

Prince Khalifa, the brother of Bahrain's previous king and the uncle of its current king, ran the day-to-day affairs of the country's government since it gained independence from Britain in 1971.

His brother, Sheikh Isa bin Salman al-Khalifa, took the seat of power in 1961 and continue to serve as the country's emir following its independence. While his brother became the ceremonial head of state, Prince Khalifa served as the head of its government and economy.

Prince Khalifa's family belongs to the al-Khalifa dynasty that ruled the region since 1783. The family continued its rule over the country while it was a British protectorate.  

Under his leadership, the country was able to overcome great economic challenges. He also helped build a strong alliance with the U.S. during his tenure. The U.S. currently has its Navy's Fifth Fleet based in Bahrain.

Prince Khalifa was present during major conflicts in the country, including the Arab Springs uprisings in 2011. He was also present at various eruptions of popular discontent, which were mostly instigated by the nation's Shiite Muslim majority.

Following his death, Bahrain announced that Crown Prince Salman bin Hamad al-Khalifa will be taking over as the country's new prime minister. The 51-year-old prince is the eldest son of the king and the current deputy commander of the country's military.