LONDON, Feb 14, 2008 (AFP) - Hopes for a last-ditch accord between Paul McCartney and his estranged wife Heather Mills hang in the balance as they prepare for the final day of behind-closed-doors hearings Friday.

The former Beatle 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.

Press reports on Tuesday said they were close to clinching a deal after both McCartney, 65, and Mills were seen smiling and looking relaxed as they emerged from the top-secret talks.

But since then hopes have faded again, and there is little indication whether an agreement can be struck before the scheduled end of the five-day legal wrangle on Friday.

If they fail to agree a private accord this week, the case will be heard in public.

'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 is claimed could be one of the costliest divorces in British legal history.

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 -- which describes itself as the definitive guide to wealth -- had made a 100-million-pound allowance for a possible divorce settlement.

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.