Kuwait's 84-year-old ruler Sheikh Sabah Al-Ahmad Al-Sabah has undergone a "successful minor surgery" at a hospital in the US, state news agency Kuna reported on Sunday.

Sheikh Sabah, who has ruled the US-allied Gulf Arab oil exporter since 2006, earned respect in the Middle East for rebuilding ties in the region after Iraq's 1990 invasion of his country.

Kuna gave no details on the surgery, but said Sheikh Sabah would remain in hospital for "the normal period of recuperation".

Illness at the top of the ruling family left Sheikh Sabah as the de facto policymaker for years before he became emir, chosen as an experienced pair of hands. - Reuters