America's oldest living ex-president George HW Bush has been hospitalised with shortness of breath.

Bush senior, 92, has been in the Houston Methodist Hospital since Saturday, family spokesman Jim McGrath told Reuters.

"Doctors and everyone are very pleased, and we hope to have him out soon," McGrath wrote in an email to Reuters. Bush is responding "very well to treatments", he said.

Bush is the father of former president George W Bush and former Florida governor Jeb Bush, who ran against President-elect Donald Trump in the 2016 Republican primaries.

Bush was hospitalised twice in 2014 with identical symptoms and spent seven weeks fighting pneumonia. He also broke a bone in his neck in 2015 when he fell at home. He suffers from a form of Parkinson's disease, which has forced him to use a motorised scooter since 2012.

In January 2013 he was also hospitalised and discharged after receiving treatment for a bronchitis-related cough.

Bush was a naval pilot during World War II and also served twice as vice-president under Ronald Reagan.

Illness has not totally curtailed his lifestyle, however, as Bush skydived from a helicopter near his home in Maine on his 90th birthday in June 2014.