Gerald Ford, who picked up the pieces of Richard Nixon's scandal-shattered White House as the 38th US president and the only one never elected to nationwide office, has died aged 93.

"My family joins me in sharing the difficult news that Gerald Ford, our beloved husband, father, grandfather and great grandfather has passed away at 93 years of age," his wife Betty Ford said in a brief statement issued from her husband's office in Rancho Mirage, California.

"His life was filled with love of God, his family and his country."

He died at 6.45pm local time on Tuesday at his home in Rancho Mirage, 130 miles east of Los Angeles. No cause of death was released.

Ford was the longest living president, followed by Ronald Reagan, who also died at 93.

"The American people will always admire Gerald Ford's devotion to duty, his personal character and the honourable conduct of his administration," President George Bush said in a statement.

"We mourn the loss of such a leader, and our 38th president will always have a special place in our nation's memory. I was deeply saddened this evening when I heard of Gerry Ford's death," former first lady Nancy Reagan said in a statement. "Ronnie and I always considered him a dear friend and close political ally."

Ford was an accidental president, Nixon's hand-picked successor, a man of much political experience who had never run on a national ticket. He was as open and straightforward as Nixon was tightly controlled and conspiratorial.

Minutes after Nixon resigned in disgrace over the Watergate scandal and flew into exile, Ford took office and famously declared: "Our long national nightmare is over."

But he revived the Watergate debate a month later by granting Nixon a pardon for all crimes he committed as president. That single act, it was widely believed, cost Ford election to a term of his own in 1976, but it won praise in later years as a courageous act that allowed the nation to move on.

The Vietnam War ended in defeat for the US during his presidency with the fall of Saigon in April 1975.

Evoking Abraham Lincoln, he said it was time to "look forward to an agenda for the future, to unify, to bind up the nation's wounds".

Ford was in the White House only 895 days, but changed it more than it changed him.

Even after two women tried separately to kill him, the presidency of Gerry Ford remained open and plain.

After the Watergate ordeal, Americans liked their new president - and first lady Betty, whose can-dour charmed the country.

She remained one of the country's most admired women even when she was admitted to hospital in 1978 and admitted to having become addicted to drugs and alcohol she took for painful arthritis and a pinched nerve in her neck. Four years later she founded the Betty Ford Centre for substance abusers.

In the 1976 election Ford survived an intraparty challenge from Ronald Reagan only to lose to Democrat Jimmy Carter. He ignored Carter's record as governor of Georgia, concentrating on his own achievements.