A Saudi prince has been ordered by the High Court in London to give evidence in a multi-million pound legal battle with a woman who says she was secretly married to his late father.

If Prince Abdul Aziz – son of the late King Fahd – does not attend, he could force contempt proceedings – and possible arrest if he enters the UK, a judge warned.

The judge made the order even though he was told that the prince has been “forbidden” by his uncle King Salman from flying to the UK to appear in the witness box.

The judge was told there were fears of the Saudi royal family being caught up in “a media circus”.

The judge made his order on the first day of a claim being made by Janan Harb that she was secretly married to King Fahd – then a minister of the interior of Saudi Arabia – in 1968 when she was 19.

Prince Aziz wants to rely on witness statements signed by him, and witnesses called on his behalf. Lawyers for the prince said it was impossible for him to attend because of the stance being taken by the royal household.

But Mr Justice Peter Smith said: “I do not accept at the moment that if I make an order he will not attend.”

The judge warned that if the prince failed to appear in court next Tuesday it was possible that he would be in contempt of court.

Ms Harb, who was in court to give her own evidence, claims that she and Prince Aziz had a meeting at the Dorchester Hotel in London in the early hours of June 20 2003.

She says the prince entered into a binding agreement to pay her £12m and transfer back to her two flats in Chelsea, west London, in order to satisfy promises given by his father to provide for her financially for the rest of her life.

The judge said the prince denied her claim, and “the linchpin” of the case was “who do I believe?”

The way to obtain “best evidence available to decide who is being truthful” was by way of oral testimony and cross examination.