Prince Bandar had a palatial residence in Aspen

After his resignation in 2005, the prince was appointed head of the newly created National Security Council, responsible for tackling Islamist militants in the kingdom.

But the son of Crown Prince Sultan bin Abdul Aziz and brother-law-of Foreign Minister Saud al-Faisal bin Abdul Aziz remains a key figure in Saudi Arabia's international affairs.

A man of extraordinary drive and energy with a lavish and colourful lifestyle the former fighter pilot was once described as an "Arab Gatsby".

He has enjoyed unparalleled access to centres of power in the US and played an important behind-the-scenes role in diplomacy and international deals.

This has continued since his sudden departure from the Washington embassy, for "personal reasons" according to a statement, just weeks before the death of King Fahd and the elevation of his father to heir apparent.

Prince Bandar has been particularly close to the Bush dynasty and their allies such as Vice President Dick Cheney, who served as defence secretary under President George HW Bush.

The current president is even said to have earned the nickname Bandar Bush, as an honorary member of the family.

'Charming and effective'

Prince Bandar's stratospheric connections in Washington were laid out in Washington Post journalist Bob Woodward's account on the build-up to the US-led invasion of Iraq in 2003, Plan of Attack.

He played a very central role in the relationship between Washington and Riyadh Richard Fairbanks Former US ambassador-at-large

Mr Woodward claims that in January 2003, Prince Bandar was shown essential details of the war plan against Saddam Hussein, even before then Secretary of State Colin Powell.

Amid prospects of a steep rise in oil prices, Prince Bandar is said to have casually mentioned that the Saudis hoped to increase oil production so as to hold petroleum prices down.

He requested and received a subsequent meeting with the president himself, Mr Woodward says.

Richard Fairbanks, US ambassador-at-large under President Reagan and former chief US negotiator for the Middle East peace process, has known Prince Bandar professionally and socially for many years.

"He is very smart, charming and a very effective diplomat," he told the BBC.

Mediating US-Saudi ties was significantly harder post-9/11

"He started out as an ad hoc emissary, and later became ambassador, and he... played a very central role in the relationship between Washington and Riyadh."

The task of mediating the US-Saudi relationship became significantly harder after the 11 September 2001 attacks, in which the majority of hijackers were Saudi nationals.

"He has lowered his profile, but it has not altered his effectiveness as a diplomat," Mr Fairbanks said.

Mid-East role

In an interview in 2003, Prince Bandar told the New Yorker magazine his biggest disappointment was the failed talks to resolve the Middle East conflict.

He was referring to negotiations in the last weeks of the Clinton presidency, in which he played an unpublicised role.

However, he has had a chance to redeem the Israeli-Palestinian situation, even if the conflict itself shows little sign of a solution.

Despite Saudi Arabia's diplomatic boycott of Israel, Israeli media reports say he secretly met Prime Minister Ehud Olmert in September 2006 for discussions on a Saudi peace plan - which has been gaining momentum after the collapse of Israel's own unilateral model.

The prince is also said to be behind the Mecca agreement between Fatah and Hamas for the establishment of a Palestinian unity government.

Born in Taif in 1949, he is reportedly the son of an African-born slave or concubine, and was initially not recognised by his father as a son and heir.

Bandar graduated from the Royal Air Force College at Cranwell, England and also trained at Maxwell Air Force Base in the US.

In 1968 he was commissioned in the Royal Saudi Air Force and had a 17-year career in the military flying numerous fighter aircraft.