19/11/01: The fate of John O'Neill, the Irish-American FBI agent who for years led US investigations into Osama bin Laden's al-Qaeda network, is the most chilling revelation in the book Bin Laden: The Hidden Truth, published in Paris this week.

O'Neill investigated the bombings of the World Trade Centre in 1993, a US base in Saudi Arabia in 1996, the US embassies in Nairobi and Dar-Es-Salaam in 1998, and the USS Cole last year.

Jean-Charles Brisard, who wrote a report on bin Laden's finances for the French intelligence agency DST and is co-author of Hidden Truth, met O'Neill several times last summer. He complained bitterly that the US State Department - and behind it the oil lobby who make up President Bush's entourage - blocked attempts to prove bin Laden's guilt.

The US ambassador to Yemen, Ms Barbara Bodine, forbade O'Neill and his team of so- called Rambos (as the Yemeni authorities called them) from entering Yemen. In August 2001, O'Neill resigned in frustration and took up a new job as head of security at the World Trade Centre. He died in the September 11th attack.

Brisard and his co-author Guillaume Dasquié, the editor of Intelligence Online, say their book is a tribute to O'Neill. The FBI agent had told Brisard: "All the answers, everything needed to dismantle Osama bin Laden's organisation, can be found in Saudi Arabia."

But US diplomats shrank from offending the Saudi royal family. O'Neill went to Saudi Arabia after 19 US servicemen died in the bombing of a military installation in Dhahran in June 1996. Saudi officials interrogated the suspects, declared them guilty and executed them - without letting the FBI talk to them. "They were reduced to the role of forensic scientists, collecting material evidence on the bomb site," Brisard says.

O'Neill said there was clear evidence in Yemen of bin Laden's guilt in the bombing of the USS Cole [in which 17 US servicemen died] but that the State Department prevented him from getting it."

Brisard and Dasquié discovered that the first country to issue an international arrest warrant against bin Laden was not the US, but Moamar Gadafy's Libya, in March 1998. The confidential notice, published for the first time in their book, was sent by the Libyan interior ministry to Interpol on March 16th, 1998, and accuses bin Laden of murdering two German intelligence agents, Silvan Becker and his wife, in Libya in 1994.

Bin Laden supported a fundamentalist group called al-Muqatila, made up of Libyans who had fought with him against the Soviets in Afghanistan.

Al-Muqatila wanted to assassinate Gadafy, whom it considered an infidel. According to the former MI5 agent David Shayler, British intelligence - also in league with al-Muqatila - tried to assassinate Gadafy in November 1996.

It was because of British collaboration with al-Muqatila that the Interpol warrant was ignored, Brisard says. Since September 11th, al-Muqatila has been placed on President Bush's list of "terrorist groups".

The central thesis of Brisard and Dasquié's book is sure to join the annals of 21st century conspiracy theories. The writers document negotiations between the Bush administration and the Taliban between February and August of this year.

Less convincingly, they conjecture that the September 11th suicide attacks were the result of the failure of those negotiations.

The chief motivation behind US attempts to make peace with the Taliban can be summed up in one word: oil. The former Soviet republics of Central Asia - Turkmenistan, Uzbekistan and especially "the new Kuwait", Kazakhstan - have vast oil and gas reserves. But Russia has refused to allow the US to extract it through Russian pipelines and Iran is considered a dangerous route. That left Afghanistan.

The US oil company Chevron - where Mr Bush's National Security Advisor Condoleeza Rice was a director throughout the 1990s - is deeply involved in Kazakhstan. In 1995, another US company, Unocal (formerly Union Oil Company of California) signed a contract to export $8 billion worth of natural gas through a $3 billion pipeline which would go from Turkmenistan through Afghanistan to Pakistan.

The authors recall how the State Department applauded the Taliban takeover in September 1996, five months after a US assistant secretary of state warned "economic opportunities will be missed" if political stability was not restored in Afghanistan.

Laila Helms, the part Afghan niece of the former CIA director and former US ambassador to Tehran Richard Helms, is described as the Mata-Hari of US-Taliban negotiations.

Ms Helms brought Sayed Rahmatullah Hashimi, an adviser to Mullah Omar, to Washington for five days in March 2001 - after the Taliban had destroyed the ancient Buddhas of Bamiyan. Hashimi met the directorate of Central Intelligence at the CIA and the Bureau of Intelligence and Research at the State Department.

In negotiations which continued until July, the US then took a more discreet position, letting the UN envoy Francesc Vendrell do most of the work and appointing a former US ambassador to Pakistan, Thomas Simons, to represent the US at informal meetings in Berlin.

The last direct US contact with the Taliban was on August 2nd, 2001, when Christina Rocca, the director of Asian affairs at the State Department, met the Taliban ambassador in Islamabad. Ms Rocca was previously in charge of contacts with Islamist guerrilla groups at the CIA, where in the 1980s, she oversaw the delivery of Stinger missiles to Afghan mujaheddin.

Last February, the Taliban had indicated it might be willing to hand over bin Laden, but by June, according to Brisard and Dasquié, the US began considering military action. "The US thought they could 'decouple' Osama bin Laden from the Taliban," Brisard says. "What they did not understand was that without bin Laden, the Taliban regime wouldn't have existed."

By dispatching Francesc Vendrell to see the exiled King Zaher Shah in Rome and raising the threat of military action, Washington "backed the Taliban into a corner", the authors say. For the Taliban - assuming its leadership had advance knowledge of the suicide attacks - September 11th was a sort of pre-emptive strike.

Brisard and Dasquié claim a significant part of the Saudi royal family supports bin Laden. "Saudi Arabia has always protected bin Laden - or protected itself from him," says Brisard. He points out that attacks inside the kingdom targeted US interests, never the Saudis.

Khalid bin Mahfouz is the former chairman of the kingdom's biggest bank, the National Commercial Bank, who, with 10 family members received Irish citizenship in December 1990. Brisard and Dasquié call him "the banker of terror".

The 73-year-old Mahfouz is now under house arrest in the Saudi resort of Taif, accused by the FBI and CIA of having diverted $2 billion to Islamic charities that helped bin Laden.