London (CNN) -- Britain's "Iron Lady" will be hospitalized through Christmas after undergoing surgery to remove a growth in her bladder, the Press Association news agency reported Monday.
Former Prime Minister Margaret Thatcher, 87, was doing "absolutely fine" after the operation last week, spokeswoman Gillian Penrose said Friday.
But a spokesman said that given Thatcher's age, he doesn't expect the ex-premier to leave the hospital for a few more days, the Press Association said.
Britain's only female prime minister, Thatcher served from 1979 to 1990 as leader of the Conservative Party. She was called the "Iron Lady" for her personal and political toughness.
She enjoyed a close friendship and working relationship with the late U.S. President Ronald Reagan, with whom she shared similar conservative views.
Thatcher retired from public life after a stroke in 2002 and suffered several strokes after that.
She makes few public appearances. Thatcher missed a reception in honor of her 85th birthday hosted by Prime Minister David Cameron in October 2010 and skipped the unveiling of a statue of Reagan in London in July last year.
CNN's Per Nyberg and Melissa Gray contributed to this report.