Pop superstar Madonna and her movie director husband Guy Ritchie have reportedly called in accounting firm MGR as part of preparations for a divorce.

The firm has been instructed to go through the couple's books to decipher which assets are owned separately and which are shared to help lawyers work out the level of settlement to be awarded, according to the Daily Mirror.

The couple share a £7m house in London plus another in the country and Madonna is thought to want the matter resolved as quickly as possible.

It is understood that no prenuptial agreement was signed by the pair prior to their marriage, making MGR's role crucial in deciding how much of Madonna's estimated £380million fortune Ritchie will receive. Figures of up to £50m have been mentioned in the press.

MGR and its associated businesses handle the accounting affairs of many celebrities, including John Cleese, Stephen Fry, Steve Coogan, Emma Thompson, Michael Winner and the Sugarbabes.