A woman who says she is the "secret wife" of the late King Fahd of Saudi Arabia has won her claim at the High Court in London for a multimillion-pound payout to honour a promise that she would be looked after "for the rest of my life".

A judge ruled that Palestinian-born Janan Harb, 68, was entitled to over £15 million plus the value of two expensive London properties.

The judge ruled "credible" her claim to a payout. Miss Harb told the court she had secretly married the king in 1968 when she was 19 and he was still a prince and his country's minister of the interior.

Ms Harb said Prince Abdul Aziz - son of another wife of the king - met her at the Dorchester Hotel in London on June 20 2003 when the king was seriously ill.

In the early hours of the morning he agreed to pay her £12 million and transfer back to her two flats in Pier House, Cheyne Walk, Chelsea, London, to keep his father's promise of lifelong financial support.

The prince made written statements to the court denying her claim.

But Chancery Division judge Mr Justice Peter Smith said he accepted Ms Harb's claim and ruled there had been an agreement.

During the hearing of the case, the judge ordered Prince Abdul Aziz to attend court in person to give evidence but was told the current Saudi monarch King Salman and the royal family feared that his appearance would result in "a media circus".

His failure to obey the judge's order led to him being ordered to pay £25,000 to charity for contempt of court.

The judge said the lynchpin of the case was whether he believed Ms Harb or the prince, and the best way to decide was to hear the prince give oral evidence and be cross-examined, as Ms Harb had done.

After the ruling, Ms Harb said: "This has been 12 years of misery for me. I am very happy with British justice.

"Thank God we have British justice. The prince wanted me to go to Saudi Arabia where he would had power over all this.

"I am very relieved. I only wish he could have honoured his father's wishes... he is being very mean."

"This is a very difficult case. I really thank the judge so much. He was so understanding."

The judge said his ruling had "turned on the credibility of the claimant (Ms Harb)".

He ordered lawyers acting for the prince to pay £12 million into court within 28 days, pending a possible appeal to the Court of Appeal against his ruling.

Unless the ruling is overturned, the total payment to Ms Harb is expected to be more than £15 million, plus the transfer into her ownership of the two Cheyne Walk apartments - each estimated to be worth about £5 million - or the recovery of sums equal to their value.

During a hearing over seven days in July, Ms Harb told the court that members of the family of King Fahd, who died in 2005, were opposed to their relationship as she was from a Christian family in Palestine.

She said in a statement: "Fahd was concerned about how this would be viewed by the Saudi public, many of whom follow a strict interpretation of Islam that preaches deep enmity and hostility to all other religions. It was for this reason that in March 1968 we underwent a discreet ceremony of marriage."

Ms Harb said she converted to Islam shortly before the ceremony.

Over the next three years she fell pregnant three times but each time had an abortion at Fahd's request "because of his concern over the outcry if it had become known that Fahd had fathered a child with a woman from my background".

Ms Harb said she was banished from Saudi Arabia by the king's immediate family in 1970 after they "wrongly" blamed her for his addiction to methadone.

She thought then that banishment had led to a divorce, and she went on to have two further marriages, both of which ended in divorce. The king also married again and had a number of children, including Prince Abdul Aziz.