George Shultz, a former US secretary of state who significantly shaped foreign policy in the late 20th Century, has died at the age of 100.

He died at his home in Stanford, California, the Hoover Institution think tank said.

He served three Republican presidents – Dwight Eisenhower, Richard Nixon and Ronald Reagan – in various roles.

Under Mr Reagan, Mr Schultz spent much of the 1980s trying to improve relations with the Soviet Union.

The Hoover Institution, where Mr Schultz worked as a distinguished fellow, said the statesman had been instrumental “in changing the direction of history by using the tools of diplomacy to bring the Cold War to an end”.

Hoover Institution Director Condoleezza Rice – a former secretary of state herself – said: “Our colleague was a great American statesman and a true patriot in every sense of the word.”

“He will be remembered in history as a man who made the world a better place.”