A file picture taken in 2010 of former British Prime Minister, Baroness Margaret Thatcher.

London -

Britain's former prime minister Margaret Thatcher and former US president George H.W. Bush are both likely to remain in hospital over Christmas.

Thatcher was “in good spirits” in hospital on Sunday, her spokesman said, as she continues her recovery from a bladder operation.

Thatcher, 87, was admitted to hospital on Thursday for a minor operation to remove a growth in her bladder after suffering pain earlier in the week.

“I understand she is in good spirits,” a spokesman said.

“Given her age, I don't think she will be coming out for a few days.”

The former Conservative Party leader was Britain's prime minister from 1979 to 1990. She remains Britain's only female premier.

Earlier Sunday, public relations executive Lord Tim Bell, who advised the “Iron Lady” for her three general election victories, said Thatcher was doing “fine”.

“She is (at the hospital) at the moment and she's fine,” he told AFP.

He said that her daughter Carol was at her side and that he had “no idea at all” when Thatcher would leave hospital.

Bell has described the operation as “minimally invasive surgery”.

On Friday, current Conservative Prime Minister David Cameron's office wrote on Twitter that the “PM wishes Lady Thatcher a speedy recovery”.

In recent years, Thatcher - the 20th century's longest continuous occupant of 10 Downing Street - has cut a subdued figure.

After a series of minor strokes, she was told by doctors to quit public speaking in 2002. With dementia taking hold, she has appeared increasingly rarely in public.

Her daughter once revealed that the former premier had to be repeatedly reminded that her husband Denis had died in 2003.

Meanwhile, Bush, who has been hospitalised for a month undergoing treatment for bronchitis, may not be released from a Houston hospital in time to celebrate Christmas at home as doctors had hoped.

Bush, 88, remained in stable condition and doctors were optimistic he would make a full recovery, George Kovacik, a spokesman at Methodist Hospital, said in an e-mailed statement on Sunday.

But doctors were being "extra cautious" with his care and no discharge date had been set, the statement said. Earlier this month, Kovacik said doctors expected Bush would be able to spend Christmas at home with his family.

"His doctors feel he should build up his energy before going home," the statement said.

Bush, the 41st president and a Republican, took office in 1989 and served one term in the White House. The father of former President George W. Bush, he also is a former congressman, UN ambassador, CIA director and vice president for two terms under Ronald Reagan. - Reuters, Sapa-AFP