A handwritten journal containing Osama Bin Laden's 'operational ideas' was among the items obtained in the raid on his compound in Pakistan by US special forces.

Agents are studying the notebook for information on future al-Qaeda plots.

However, a US official described it as 'just one of many things' found along with computers, hard drives, DVDs, flash drives and recording devices.

There were no 'warm and fuzzy' personal or emotional passages, he said. It was 'more just jotting down some ideas. It doesn't entail where he's been or what he's done'.

Meanwhile, the CIA has begun showing US politicians photos of the dead Bin Laden that President Barack Obama said were too gruesome to be released to the public.

Senator James Inhofe, a Republican from Oklahoma, said he was shown 15 photographs taken of Bin Laden after he was killed on 2 May.

In an interview with CNN, Mr Inhofe agreed that the photos taken immediately in the compound in Pakistan immediately after Bin Laden was killed were 'pretty gruesome'.

'One of the shots went through an ear and out through the eye socket. Or it went in through the eye socket and out - then exploded,' he said.

'That caused the brains to hang out of the eye socket, so that was pretty gruesome.'

Mr Inhofe said he had no doubt the man was Bin Laden.

'Absolutely, no question about it. I've seen them. That was him. He's gone. He's history,' he said.

In deciding not to release the pictures to the public, the White House expressed fear that they would inflame sentiment in the Middle East and be used as a propaganda tool against the US.

Meanwhile, Kenya has tightened security around the home of US President Barack Obama's step-grandmother after the killing of Osama bin Laden.

There have been no direct threats against the family but Kenya is on alert following warnings from al-Qaeda followers after bin Laden was killed by US special forces in Pakistan on 2 May.

The elderly Sarah Obama's homestead has been guarded since her step-grandson was elected president in 2008.

Sarah Obama was the third wife of President Obama's paternal grandfather, Hussein Onyango Obama. Although not a blood relation, Obama often refers to her as his grandmother.

The Kenyan government in 2009 officially listed Sarah Obama's Kogelo village, near the border with Uganda, a protected national heritage site in a bid to boost tourism.