Former President George HW Bush wrote a personal note to President-elect Donald Trump explaining that he is under doctor's orders to skip the inauguration ceremony.

Mr Bush, 92, says he cannot brave the cool January weather given his current health condition.

"My doctor says if I sit outside in January, it will likely put me six feet under," the 41st President wrote. "So I guess we're stuck in Texas."

Spokesperson for Mr Bush, Jim McGrath, confirmed the authenticity of the letter on Twitter.

Mr Bush had been admitted to a Houston hospital prior to the release of the letter. Former First Lady Barbara Bush was later admitted to the hospital as a precautionary measure.

"Shortly after our previous report on President Bush's condition, he was admitted to the ICU at Houston Methodist Hospital to address an acute respiratory problem stemming from pneumonia. Doctors performed a procedure to protect and clear his airways that required sedation," a spokesperson said.

"Barbara Bush was admitted to the same hospital Wednesday morning as a precaution after experiencing fatigue and coughing."

In pictures: George Bush library Show all 9 1 /9 In pictures: George Bush library In pictures: George Bush library bush-library5.jpg Workers make preparations before a dedication ceremony at the George W. Bush Library and Museum on the grounds of Southern Methodist University on 25 April 2013 in Dallas, Texas (AFP) AFP In pictures: George Bush library bush-library6.jpg Hanging large US Flag before the dedication of the George W. Bush Presidential Center (AP) AP In pictures: George Bush library bush-library8.jpg First lady Michelle Obama, and former first ladies Laura Bush, Hillary Clinton, Barbara Bush and Rosalynn Carter attend the opening ceremony of the George W. Bush Presidential Center (Getty Images) Getty Images In pictures: George Bush library bush-library10.jpg US President Barack Obama and all four living former presidents gather onstage at the dedication of the George W. Bush Presidential Center on the campus of Southern Methodist University in Dallas, Texas (Reuters) Reuters In pictures: George Bush library bush-library9.jpg From left: US President Barack Obama and former presidents George W. Bush, Bill Clinton, George W. Bush and Jimmy Carter on stage for the George W. Bush Presidential Center dedication ceremony in Dallas, Texas (AFP) AFP In pictures: George Bush library bush-library2.jpg Former Vice President Dick Cheney, center, shakes hands with former British Prime Minister Tony Blair at the ceremony (AP) AP In pictures: George Bush library bush-library3.jpg George W. Bush walks behind a military choir at the end of the dedication ceremony for his library (Reuters) Reuters In pictures: George Bush library bush-library4.jpg Former Italian Prime Minister Silvio Berlusconi arrives at the dedication of the George W. Bush Presidential Center (Reuters) Reuters In pictures: George Bush library bush-library11.jpg From left, former British Prime Minister Tony Blair, former Secretary of State Condoleezza Rice and former Vice President Dick Cheney (AP) AP

The former president suffers from a form of Parkinson's disease that has left him unable to walk unassisted, and he gets around with the help of a wheelchair.

Mr Bush was hospitalised twice in 2014. One trip to the hospital lasted for seven weeks as he suffered from pneumonia and breathing difficulties. In 2015, he was admitted to a hospital when he broke a bone in his neck while at his summer home in Maine.

Despite his health troubles, Mr Bush graciously offered his support to the incoming president.

He said that he and his wife, Barbara Bush, "will be with you and the country in spirit".