Sir Paul McCartney will wed wealthy heiress Nancy Shevell tomorrow, according to reports.

The former Beatle is expected to tie the knot at London's Westminster Register Office, where he also married his first wife Linda.

Just 30 guests will be present at the singer's third wedding, the Daily Mirror reported.

The reception will be held in his back garden afterwards, the newspaper said.

Sir Paul, 69, became engaged to Shevell earlier this year after the couple began dating four years ago in the upmarket Hamptons area of Long Island.

The millionaire musician lost his first wife in 1998 when she died of cancer.

He went on to marry former model Heather Mills, a union that ended with an acrimonious courtroom battle when they divorced in 2008.

Shevell, who sits on the board of New York's Metropolitan Transportation Authority, is said to get on well with her fiance's children.

Previously married for more than 20 years to lawyer Bruce Blakeman, she is also an executive at a New Jersey-based trucking company owned by her father.

A spokesman for the star said he could not comment on the date of the wedding.