The September 11, 2001 attacks were envisioned as a bigger strike involving 10 planes on the east and west coasts of the United States, the Washington Post said quoting a report released on Wednesday.

The date for the attacks was uncertain until weeks before they were carried out, and there is evidence as late as September 9, 2001, that ringleader Mohamed Atta had not decided whether the flight that crashed in Pennsylvania would target the US Capitol or the White House, says the report, issued by the independent commission probing the attacks.

One of the hijacking pilots apparently came close to abandoning the plot, the panel found, according to the paper.

In an overview of Al Qaeda released in a separate report earlier in the day, the paper said that the commission also found "no credible evidence" that Al Qaeda collaborated with the then Iraq president Saddam Hussein on the 9/11 strikes or any other attacks on the US.

The report, which relies on the previously classified interrogations of senior Al Qaeda operatives in US custody, says that Al Qaeda leader Osama bin Laden was deeply involved in planning the strikes, choosing the hijackers and pushing to have the attacks carried out earlier than they eventually were.

Many of his aides urged him to abandon the plot as it neared its completion in the summer of 2001, the report says.

Bin Laden "thought that an attack against the United States would reap Al Qaeda a recruiting and fundraising bonanza. In his thinking, the more Al Qaeda did, the more support it would gain. Although he faced opposition from many of his most senior advisers... bin Laden effectively overruled their objections, and the attacks went forward".

The report represents by far the most detailed and authoritative public account of the attacks since the 19 Al Qaeda hijackers commandeered four planes and crashed them into the World Trade Centre, the Pentagon and the Pennsylvania countryside.

It also comes as one of the last documents to be issued by the 10-member bipartisan panel before the release next month of its final report.

The panel also cites pieces of Federal Bureau of Investigation evidence in concluding that Atta never met an Iraqi intelligence officer in Prague on April 9, 2001, as Vice-President Cheney and some other Bush administration officials have alleged.

"Based on the evidence available -- including investigation by Czech and US authorities plus detainee reporting -- we do not believe that such a meeting occurred," the report says.

According to the report, the planning for the plot began with a proposal in 1996 to bin Laden by Khalid Sheikh Mohammed, who eventually oversaw the plot and whose statements to his US interrogators form a crucial part of the report.

Another US detainee, 9/11 financier and would-be hijacker Ramzi Binalshibh, also figures prominently in the account.

Bin Laden approved a plan in 1999 that called for hijacking airliners in both the US and Southeast Asia, but the latter part was soon dropped for logistical reasons.

In addition to the targets that were hit on 9/11, Mohammed proposed crashing hijacked planes into the CIA and FBI headquarters, unidentified nuclear power plants and the tallest buildings in California and Washington state, the report says.

"The centrepiece of his original proposal was the tenth plane, which he would have piloted himself," it says. Instead of crashing it in a suicide attack, Mohammed would have killed very adult male passenger on the plane, contacted the media from the air and landed the aircraft at a US airport. Then he would have made a speech denouncing US policies in West Asia before releasing all the women and children, the report says.

But bin Laden scrapped the idea of using one of the hijacked planes to make a public statement, the report adds.