LONDON, Feb 15, 2008 (AFP) - Former Beatle Paul McCartney and his estranged wife Heather Mills are set to continue behind-closed-doors court hearings aimed at agreeing a divorce deal next week, court officials said Friday.

The five-day hearings were to have ended Friday, but court officials said the room where the couple have been meeting with lawyers and a judge has been booked for Monday.

The deal could be the highest divorce settlement in Britain, outstripping the 48 million pounds businessman John Charman was told to pay his former wife last year.

McCartney is estimated to be worth 825 million pounds, but last year's Sunday Times Rich List, billed as the definitive guide to wealth, had made a 100-million-pound allowance for a possible divorce settlement.

The 65-year-old pop legend and the 40-year-old former model have remained tight-lipped all week since the hearings began Monday at the High Court in central London.

Entering court Friday both looked relaxed, Mills -- who is representing herself -- clutching a red file, while McCartney maintained an enigmatic expression as he talked with his lawyer.

Court officials cited by the Press Association confirmed that Court 34, where the hearings have been taking place, has been booked again for next week.

Press reports mid-week said they were close to clinching a deal after both McCartney and Mills were seen smiling and looking relaxed as they emerged from the top-secret talks.

But since then hopes have faded again, and Friday's announcement of an extension to the five-day hearings appeared to confirm their difficulty in reaching agreement.

The judge in the case would normally be expected to rule in the case within a few weeks, but details of any settlement would remain confidential.

The Daily Mail reported that McCartney could offer Mills 55 million pounds (74 million euros, 107 million dollars).

She would take a 20-million-pound lump sum and a further 2.5 million pounds each year for 14 years until their four-year-old daughter, Beatrice, turns 18, with a substantial amount set aside for security, it said.

If they fail to agree a private accord, the case would go to appeal and be heard in the full glare of publicity.

'It is possible that if the matter is not settled by agreement, (the judge) will make an order and if Miss Mills is not happy with the terms, she can apply to take her case to the Court of Appeal,' said lawyer David Ruck.

'If she is given permission, she can go to the Court of Appeal and then the whole matter will be in public,' added Ruck, of law firm Gordon Dadds.

McCartney and Mills were last in court in October but failed to agree a financial settlement in what could be one of the costliest divorces in British legal history.

The musician married Mills in 2002, four years after his first wife, Linda, died from breast cancer. They announced an 'amicable' split in May 2006, but their dealings since have been anything but friendly.