DUBAI (Reuters) - Bahrain's Prime Minister Sheikh Khalifa bin Salman al Khalifa was taken to hospital on Friday night but was in stable condition, state news agency BNA said.

"The Prime Minister entered the hospital this evening for medical tests, which were reassuring and culminated in thanks for God and his successful favour," a statement said, without elaborating on the cause of the hospitalisation.

Khalifa, 80, has served as Bahrain's prime minister since the Sunni Muslim-led island kingdom declared independence from Britain in 1971. The al-Khalifas have ruled since 1783, when they drove out Zand dynasty Persians from the area.

The kingdom is the home base of the US Navy's Fifth Fleet and has experienced sporadic unrest since mass protests in 2011 led by majority Shi'ites.