Princess Haifa is wife of Prince Bandar, who was Saudi ambassador to U.S. for 22 years

Prince Turki was ambassador to Washington and to London and previously ran country's

Claims: Zacarias Moussaoui, who is serving a life sentence for terror charges, has said Saudi Arabia financed the 9/11 attacks in an extraordinary letter from his prison cell

The man who claims he was the 20th 9/11 hijacker has named two of the most senior members of the Saudi Royal family as being the ones who paid him to carry out the terrorist attack.

Zacarias Moussaoui alleges that Prince Turki al-Faisal and Princess Haifa al-Faisal gave him cash and ‘channeled a large amount of money’ to another of the hijackers.

He also claims that Prince Faisal ‘was assisting me in my Islamic terrorist activities...and was doing so knowingly for Osama bin Laden’.

The extraordinary allegations are in a letter that Moussaoui wrote to a federal judge in Oklahoma and are likely to be seized on by 9/11 conspiracy theorists.

The letter has been entered as a prisoner civil rights complaint and has been assigned to District Judge Vicki Miles-LaGrange.

Moussaoui’s letter has already been reported but the names were not made public until MailOnline saw a copy of the full letter.

Moussaoui, 46, is currently serving life in jail after admitting his role in the 9/11 attacks, which the Saudi government has always denied involvement in.

His credibility has also long been called into question as even Osama bin Laden has denied he had anything to do with his terrorist plots.

Moussaoui wrote to the Western District Federal Court in Oklahoma because he was studying at a flight school in Norman, Oklahoma, in 2001 when he supposedly received the money from the Saudis.

He wanted to testify in open court about what he knows but last week a magistrate recommended that his request be denied as it is not related to any ongoing case.

The people that Moussaoui has named are among the most powerful in the Saudi royal family.

Prince Turki al-Faisal, 67, is a former Saudi ambassador to the United States and a former Saudi intelligence chief. He ran its intelligence service for 24 years.

He stepped down from the latter post on September 1st 2001, 10 days before 9/11. He was ambassador to London in 2003 before the invasion of Iraq and was ambassador to Washington from July 2005 until December 2006.

Prince Faisal attended Lawrenceville, a boarding school near Princeton, followed by Georgetown University before rising up the ranks in the Saudi royal family, where his brothers dominate the top posts in the Arab nation’s government.

Last year he took the unusual step of criticizing the US government and said that Saudi Arabia was sick of President Obama marking red lines then seeing them become ‘pinkish as time grew’.

Accused: Prince Turki al-Faisal is named by Zacarias Moussaoui in a letter to a federal judge as a funder of the 9/11 terror attacks. The Saudi government has always denied any involvement in the attacks or their funding

Response: The Saudi Arabian government said it had nothing whatsoever to do with the September 11 attacks

He said: ‘When that kind of assurance comes from a leader of a country like the United States, we expect him to stand by it.’

His sister Princess Faisal, 63, is the wife of another former Saudi ambassador to the US, Bandar bin Sultan, with whom she has eight children.

She has previously faced claims of involvement in 9/11 before and two of the hijackers, - Khalid al-Mihdhar and Nawaf al-Hazmi - supposedly received regular $3,500 a month payments from two friends who got it from an account in her name.

The Saudi government angrily denied the allegations at the time and said that Princess Faisal ‘wants her name cleared’.

In the 2004 9/11 Commission report said it had found no evidence of her having any involvement in the funding of the attacks.

Among Moussaoui's other extraordinary claims in the letter was that he was involved in a plot to shoot down Air Force One with President Bill Clinton on board.

He claims that World Trade Centre bomber Ramzi Yousef, who is in the same Supermax prison as him, tried to persuade him to keep quiet under a CIA deal to spare Al Qaeda mastermind Khalid Sheikh Mohammed from the death penalty after his military tribunal in Guantanamo Bay, where he is being held.

He also talks about how he handed over details of a plot to assassinate President Clinton and first lady Hillary Rodham Clinton during a trip to Cambridge in England whilst he was in office.

Lawyers for the federal government have taken Moussaoui seriously enough to interview him over the claims at the maximum security Colorado prison where he is serving a life sentence without parole.

They say he had 'relevant' material to contribute but he is problematic as a witness.

'Even if he somehow got to the point where he could testify, there would be a credibility issue,' said Carl Tobias, a professor at the University of Richmond School of Law. 'Would his testimony be valuable? That's doubtful.'

Another problem is that Moussaoui has repeatedly changed his account of his involvement in the Sept. 11 plot and has behaved erratically in court.

Close relationship: President George W. Bush with Prince Bandar bin Sultan, the then Saudi Arabian ambassador, in August 27, at Bush's Ranch in Crawford, Texas. Prince Bandar was succeeded by Prince Faisal as ambassador

'Nothing to do with me': A 2006 video message, above, purportedly from Osama Bin Laden, featured a voice saying Moussaoui was nothing to do with 9/11

Husband: Prince Bandar al-Sultan is the husband of Princess Haifa. He was ambassador to the US from 1983 until 2005, when his brother-in-law Prince Turki succeeded him. He described

Moussaoui, who refers to himself in writing as 'Slave of Allah,' was first arrested on immigration charges in August 2001 after employees of a Minnesota flight school became alarmed that he wanted to learn to fly a Boeing 747 - even though he had no pilot's license.

He was in custody on September 11, 2001, and pleaded guilty in April 2005 to conspiring with the hijackers to kill Americans.

During his three-year legal fight, Moussaoui repeatedly insulted the judge and tried to fire his lawyers.

At one point he was facing the death penalty, which jurors decided against. During the hearing he spontaneously declared that he had planned to pilot a plane into the White House on September 11.

A psychologist called by his lawyers testified that Moussaoui had paranoid schizophrenia. Moussaoui mocked the testimony, shouting as he left courtroom: 'Crazy or not crazy? That is the question.'

In 2006 a recording emerged online of Osama bin Laden distancing himself from Moussaoui.

He said: 'He had no connection at all with September 11. I am the one in charge of the 19 brothers, and I never assigned brother Zacarias to be with them in that mission.'

Although the audio was seen as ruling him out of the 9/11 attacks, it did not make clear if he was an al Qaeda operative.

Last month, lawyers in a federal lawsuit against Saudi Arabia were permitted to interview Moussaoui in prison.

What was said can't be shared publicly until the U.S. government finishes sifting through the transcript to ensure it contains no secret messages that could pose a threat to Americans.

Verdict: the report of the commission into the attacks said it had found no evidence 'that the Saudi government as an institution or senior Saudi officials individually funded the organization'

Jerry S. Goldman, a lawyer who interviewed him, said: 'I will say that we believe it was relevant and material to our case.'

Moussaoui also wrote to the clerk in federal court in Brooklyn in September, saying he had seen a report on Fox News about another suit accusing the Jordan-based Arab Bank of helping finance suicide bombings in Israel. He said he was willing to testify, but the plaintiffs never took it seriously.

The communication wasn't relevant to the Arab Bank case and 'don't make clear what his motives are,' said one lawyer, Gary Osen. 'I don't know his state of mind at all.'

At Supermax, Florence ADX - known as the 'Alcatraz of the Rockies' - Moussaoui is subject to restrictions requiring screening of any attempt to communicate with the outside world. However, there are exceptions for court filings.

MailOnline has reached out to the Saudi embassy to the US for comment.

Previously Prince Bandar highlighted the findings of the 9/11 Commission report. When it was published in 2004 it concluded that it had found 'no evidence that the Saudi government as an institution or senior Saudi officials individually funded the organization' of the attacks.

At the time Prince Bandar said: 'The 9/11 Commission has confirmed what we have been saying all along. The clear statements by this independent, bipartisan commission have debunked the myths that have cast fear and doubt over Saudi Arabia.’

The report directly addressed Princess Haifa al-Faisal. It said: 'We have found no evidence that Saudi Princess Haifa al Faisal provided any funds to the conspiracy, either directly or indirectly.'