Mills McCartney gave birth in October

Mills, 36, will have an operation to replace the metal plates in her pelvis, inserted after a road accident in which she lost a leg.

The problem arose after the baby, delivered by Caesarean, put extra strain on her pelvis during pregnancy,

The landmine campaigner, who gave birth to daughter Beatrice in October, will undergo surgery in the coming weeks.

A spokeswoman for Mills said: "The plates were put in after her accident - it is impossible to under-estimate the seriousness of the injuries she suffered in that crash."

"This will be a big operation but Heather is keen to get it out of the way as soon as possible because she doesn't want to take too much time off work."

Charity work

Mills was critically injured when she was hit by a police motorcycle as she crossed a road in 1993.

The former model's left leg was amputated below the knee and she was fitted with a prosthetic limb.

The accident led her to form the Heather Mills Heath Trust, recycling prosthetic limbs and campaigning against landmines.

She is now founding patron of UK charity Adopt A Minefield, along with her husband.

It was through her charity work that she met former Beatle Sir Paul McCartney, marrying him in 2002.