Image caption Bin Laden reportedly believed that only a body count of thousands would shift US policies

Osama Bin Laden calculated how many Americans would have to be killed to force the US from the Middle East, US officials say, citing his seized journal and other files.

The al-Qaeda leader reportedly wrote that smaller attacks since 9/11 were not having the desired impact.

Bin Laden also urged his followers to strike smaller cities and hit trains.

The documents were seized during last week's US raid on Bin Laden's hideout in Pakistan in which he was killed.

The US officials, who spoke to the Associated Press news agency on condition of anonymity, say Bin Laden's personal, handwritten diary and computer files reveal his hand in every recent major al-Qaeda threat.

Separately, members of US Congress are being shown photos of Bin Laden taken immediately after he was shot dead.

Oklahoma Republican Senator James Inhofe described the photos as "pretty gruesome".

One of the shots appeared to have either entered or exited through an ear, he told CNN.

Parts of Bin Laden's brain were hanging out of his eye socket, Mr Inhofe said.

Committees to see photos

The al-Qaeda threats included plots in Europe last year that saw travellers and embassies on alert, according to the two officials.

Bin Laden envisaged attacks being staged on significant dates, such as America's 4 July Independence Day and the 10th anniversary of the attacks of 11 September 2001.

He wrote that other American cities such as Los Angeles should be considered for targeting, not just New York.

In his writings, US officials say that Bin Laden wondered how many American deaths it would take to lead Washington to reconsider its policies on the Middle East.

The al-Qaeda leader is said to have concluded that only a body count of thousands, like that of the 9/11 attacks, would be enough.

Intelligence agents are continuing to analyse the documents - said to be on around 100 flash drives and five computers - seized in the 2 May raid in Abbottabad by the US Navy Seals.

Bin Laden's communications are believed to have been in missives sent via the flash drives, as his compound had no telephone or internet access.

The CIA meanwhile has said it plans to allow members of four US congressional committees to view images of Bin Laden's body.

Until now, the US authorities had been saying the pictures of Bin Laden - who was shot in the face and chest - were too gruesome to be made public and could inflame sentiment.

On Wednesday, Bin Laden's sons criticised the US for carrying out his "arbitrary killing".

A statement given to the New York Times newspaper said the family wanted to know why the al-Qaeda leader had not been captured alive.

Another statement appeared on a jihadist website saying the burial of Bin Laden at sea "demeans and humiliates his family".

US officials have said that while Bin Laden was unarmed he had given no indication to the US troops that he wanted to surrender.

Attorney General Eric Holder has said that the killing was lawful and "an act of national self-defence".