The couple met through charity work

The former Beatle reportedly told The Sun that there is "no problem" between Mills and his daughter, Stella.

"My wife is a really good woman, but people don't like to accept that," he is quoted as saying.

Mills McCartney, who married Sir Paul in 2002, has endured a barrage of press criticism and reports of friction within the family.

Rumours in the press regarding the relationship between Mills McCartney and fashion designer Stella have been circulating for some time.

Sir Paul is quoted in The Sun as saying: "I'm sick of people saying Heather and Stella don't get on - the truth is they do."

Charity work

He reportedly told the newspaper that his wife was always going into his daughter's shop to buy things.

Mills McCartney, 36, who lost a leg in an accident with a police motorcycle in 1993, used to be a model and is now an anti-landmines campaigner.

The Sun says Sir Paul told it his wife is not a publicity seeker.

"The truth is, Heather never seeks publicity for all the work she does with her landmines charity.

"And yet all that people do is knock her. They don't see all of the things that she does without asking for any thanks or recognition," he is quoted as saying.

The pair married in June 2002 and Mills McCartney gave birth to the couple's first child, Beatrice Milly, last October.

Sir Paul has four other children from his marriage to first wife Linda who died of cancer in 1998, including his step-daughter Heather, Linda's daughter from a previous marriage.