By Aziz El Yaakoubi
DUBAI (Reuters) - Bahrain's Sheikh Khalifa bin Salman al Khalifa, the world's longest serving prime minister who put down opposition unrest repeatedly during his near half century in power, has died, authorities said on Wednesday.
Sheikh Khalifa, a dominant figure in the Gulf Arab island's politics, passed away on Wednesday morning at Mayo Clinic hospital in the United States, Bahrain's state news agency said.
Khalifa, 84, the uncle of King Hamad bin Isa al-Khalifa, had served as prime minister since the Sunni Muslim-led island kingdom declared independence from Britain in 1971. The al-Khalifa family has ruled since 1783.
His stern response to pro-democracy protests in Bahrain in 2011 -- and criticism of similar unrest across the Arab world -- underlined what for many was the defining characteristic of his career, namely a stalwart defence of dynastic rule.
"The death of the world's longest serving prime Minister will be welcomed by many of Bahrain's political opposition, as he is regarded as one of the chief architects of an increasingly repressive state," said Marc Owen Jones, Assistant Professor of Middle East Studies at Hamad bin Khalifa University in Qatar.
Sayed Ahmed Alwadaei, a prominent Bahraini rights campaigner exiled in Britain, said Sheikh Khalifa had masterminded "brutal repression" of the opposition during the 1990s and oversaw the crackdown on the 2011 uprising.
Human rights groups have criticised Bahrain's Western allies, notably the United States and Britain, for often remaining silent about allegations of human rights abuses against the Shi'ite majority.
The two countries have a particularly high level of influence in Bahrain, where the U.S. Fifth Fleet is based and where Britain's Royal Navy has a major facility.
There was no immediate word about Sheikh Khalifa's successor as prime minister, a role which the constitution says is appointed by the king.
"While his succession is unclear it paves the way for the growing unencumbered influence of the crown prince, who will have more of a say in social and perhaps economic affairs," own Jones said.
Sheikh Salman bin Hamad Al Khalifa, since his appointment as Crown Prince in 1999, has become known as the ruling family's leading proponent of reform, although most meaningful changes were consistently blocked by family hardliners such as Sheikh Khalifa.
In August, Sheikh Kahlifa left the kingdom for what official media called at the time "a private visit abroad".
Earlier this year he spent time in Germany for unspecified medical treatment, returning to Bahrain in March.
The burial ceremony will take place upon the repatriation of his body and the funeral will be limited to a specific number of relatives, Bahrain's state news agency said.
Official mourning has been declared for a week and government ministries and departments will close for three days starting Thursday.