Margaret Thatcher is "absolutely fine", a spokeswoman says, after undergoing a minor operation to have a growth removed from her bladder.

Margaret Thatcher (Reuters)

The former prime minister, 87, was admitted to hospital on Thursday after experiencing pain earlier in the week. It is understood that she may remain in hospital over Christmas as she recovers from the "minimally invasive surgery".

She has been accompanied by her daughter, Carol, in hospital. Her son Mark is believed to be on holiday overseas.

Tim Bell, the PR and advertising figure who was a close adviser to the baroness, told the BBC: "The operation was a complete success and her condition is satisfactory. She'll stay in hospital for a few more days and then she'll go home.

"She's very tough. The doctors are perfectly happy. They say the operation has been completely satisfactory."

Baroness Thatcher has suffered from ill health in recent years. She was not well enough to join the Queen and other former prime ministers for a lunch as a part of the jubilee celebrations in the summer, and two years ago missed an 85th birthday party thrown for her by David Cameron.

Downing Street said that Mr Cameron wished the baroness "a speedy recovery".