Former U.S. President Gerald Ford is seen in this June 5, 2000 file photo.

Ford, who was born on July 14, 1913, in Omaha, Nebraska, has been alive for 93 years and 121 days, one day more than Reagan, who was 93 years, 120 days when died June 5, 2004.

Ford, a former Michigan congressman and vice president, became US 38th president on August 9, 1974, after Richard Nixon resigned over the Watergate scandal.

The only US president who was not elected to either the presidency or vice presidency, Ford remained in office until Jimmy Carter replaced him in January 1977 after losing the November 1976 election.

Ford and former first lady Betty Ford, 88, live in Rancho Mirage in the desert of Southern California.

"The length of one's days matters less than the love of one's family and friends," Ford said last week in a statement in the local Desert Sun newspaper.

"I thank God for the gift of every sunrise and, even more, for all the years he has blessed me with Betty and the children, with our extended family and the friends of a lifetime," he added.

Ford has suffered a variety of health problems in recent years.

The other living former presidents are Carter, 82; George H.W. Bush, 82; and Bill Clinton, 60.