Washington: In his final days, Al Qaeda chief Osama bin Laden was planning assassination attempts against US President Barack Obama and another attack on the American soil, according to a media report here on Saturday.

"Tapping away at his computer in the study of the suburban compound in Abbottabad Laden wrote memos urging his followers to continue to try to attack the US, suggesting, for instance, they mount assassination attempts against President Obama and Gen David Petraeus," the CNN's National Security
Analyst Peter Bergan wrote. At that time, Petraeus was the commanding general of NATO forces in Afghanistan.

"Bin Laden noted snidely that killing Obama would pave the way for Vice-president Joe Biden to assume the presidency. The al Qaeda leader said Biden was "totally unprepared" for the job," Bergan wrote based on the background briefing he received from the administration officials this week, who had access to the treasure trove of documents recovered from the Abbottabad hideout of the al Qaeda leader.

According to them, Bin Laden wrote a 48-page memo to a deputy in October 2010 that surveyed the state of his organization. He was particularly concerned that al Qaeda's longtime sanctuary in Waziristan in Pakistan's tribal areas was now too dangerous because of the campaign of American drone strikes there that had picked off many of his key lieutenants, it said.

"Bin Laden advised his followers not to move around the tribal regions except on overcast days when America's all-seeing satellites and drones would not have as good coverage of the area. He also urged his followers to depart the tribal regions for the remote Afghan provinces of Ghazni, Zabul and, in particular, Kunar, pointing out that the high mountains and dense forests of Kunar provided especially good protection from prying American eyes," he wrote.

The al Qaeda leader was especially concerned about the safety of his son Hamza, 20, who was recently released from house arrest. Bin Laden instructed his deputy to tell his son to move out of Waziristan.

He also provided elaborate instructions about how Hamza might evade the surveillance of the American drones in the tribal regions by meeting members of al Qaeda inside a particular tunnel on the road between the western Pakistani town of Kohat and the city of Peshawar, he said.

Bergan wrote that Bin Laden reminded his deputies that all internal communications should be made by letter rather than by phone or the internet. As a result, according to administration officials, bin Laden had to wait for responses to his queries to his deputies that could sometimes take up to two or three months to be delivered -- surely not an efficient way to run any organisation, he said.

However, there was a difference between him and deputy Ayman al-Zawahiri on launching attack on the US soil. According to administration officials, Zawahiri told Osama that it was much more realistic to attack American soldiers in Afghanistan than American civilians in the US, which al Qaeda leader was pushing for.

Bin Laden moved into his Abbottabad compound either at the end of 2005 or sometime in 2006, Bergan said quoting senior administration officials.

Bergen is also a director at the New America Foundation. His book "Manhunt: The Ten-Year Search for Bin Laden; From 9/11 to Abbottabad" will be published on May 1.

(Agencies)