WASHINGTON (AFP) - Former US president George H.W. Bush will stay at a Texas hospital through the weekend after experiencing breathing problems, but his spokesman said on Saturday he could be discharged soon.

Bush, 90, was admitted late Tuesday to Houston Methodist Hospital. He received family visits on Christmas Day, and his spokesman Jim McGrath said he was making progress.

"President Bush's condition has improved to the point that doctors have begun discussing dates for his discharge," McGrath said in a statement.

"He will remain at the Houston Methodist Hospital through the weekend for further observation."

The spokesman did not explain the reasons for the extended stay, or when Bush would leave the hospital.

The oldest of the four living former US presidents, Bush, who uses a wheelchair, seemed frail in recent public appearances. He was treated at Houston Methodist in November 2012 for bronchitis, and ended up spending nearly two months at the hospital.

The former president's wife was admitted to the same Houston hospital nearly a year ago. Suffering from pneumonia, the former first lady was released from the hospital in January.

Bush, patriarch of one of America's most prominent political dynasties, is father to former US president George W. Bush.

Another son, Jeb, last week announced that he was laying the foundation for his own 2016 White House bid.