US Senator Lindsey Graham has died after a brief and sudden illness, the communications director for his office says.

Graham, 71, was a prominent Republican senator from South Carolina. He died on Saturday night, his office said in a statement.

“Senator Graham’s family appreciates prayers at this time and asks for privacy during this incredibly difficult period,” his office added.

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Earlier in his career, Graham was a vocal critic of US President Donald Trump before becoming one of his most loyal allies on Capitol Hill.

Graham was elected to the US Senate in 2002. Before serving in the upper house, he was elected to the US House of Representatives in 1994 for South Carolina’s third congressional district, according to his website.

A defence hawk, his website said he had “consistently pushed for outcomes in the War on Terror that protect our long-term national security interests”.

Graham recently served as chairman of the Senate Budget Committee. Graham also served as a member of the Senate Committee on Appropriations, Senate Judiciary Committee and Senate Committee on Environment and Public Works.

Graham was not married and lived in Seneca, South Carolina.