A Cooper Owen auction house staffer with the guitar in London. (AP)

London, July 29 (AP): Former Beatle Paul McCartney has filed for divorce from Heather Mills McCartney, formally beginning the courtroom battle in what could be one of Britain's most expensive breakups, British newspapers reported today.

The 64-year-old artist blamed his estranged wife for the split, arguing that her behaviour was unreasonable and argumentative, The Sun and The Daily Mirror reported. Her spokesman, Phil Hall, said she was unhappy about the reports, but stopped short of confirming them.

“Heather’s going to be filing her own counterclaims about matters both in this country and America,” Hall said in a statement.

“She does not feel the need to repudiate claims that she may be headstrong or feisty,” the statement said. “She is hugely disappointed that matters of such a confidential nature should be aired in public and feels it is inappropriate to speak about such delicate matters when a child is involved.”

The couple have a 2-year-old daughter, Beatrice.

McCartney, who does not have a pre-nuptial agreement to protect his estimated US$1.5 billion (?800 million) fortune, has hired lawyer Fiona Shackleton, who represented Prince Charles in his divorce from Princess Diana.

McCartney was photographed yesterday without his wedding ring during a visit to his performing arts school in Liverpool on England’s northwest coast.

The couple married in June 2002, four years after McCartney’s first wife, Linda McCartney, died of breast cancer. Linda and Paul McCartney married in 1969, and had three children.

McCartney and Mills McCartney, a former model and animal-rights campaigner, met at a charity event in 1999.

First guitar auctioned

An American collector has bought McCartney’s first acoustic guitar for ?330,000 pounds ($614,000) at an auction. The guitar used by McCartney was bought by Craig Jackson at an auction at the Abbey Road Studios late yesterday. “This is such an important piece of rock history, and I am an extremely happy man tonight,” Jackson said in a statement.