Details of communication between al Qaeda leaders derived from Osama bin Laden's computers indicate that the terror network is facing massive financial crunch and difficulties in replacing cadres lost in combat with US-led coalition forces in Afghanistan, Pakistan and other places, a media report said today.

During the six weeks of intensive study of the material obtained from Abbottabad compound of Osama bin Laden, where he was killed by US Special Forces on May 2, the CIA-led inter-agency team have prepared some 400 intelligence reports.

The most important information gleaned from the 15 computers and 100 storage devices recovered from bin Laden's compound is the information about the internal strains of the terrorist outfit and the repeated attempt of bin Laden to carry out attacks on the US, The Washington Post reported.

"The trove makes it clear that bin Laden's primary goal — you can call it an obsession — was to attack the US homeland," a senior US counter-terrorism official was quoted as saying.

"He pushed for this every way he could," he added.

According to The Washington Post over the past year, the al-Qaeda leader fielded e-mails from followers lamenting the toll being taken by CIA drone 'explosions' as well as the network's financial plight.

"Bin Laden approved the creation of a counter-intelligence unit to root out traitors and spies, only to receive a complaint in mid-2010 from the unit's leader that it was losing the 'espionage war' and couldn't function on its paltry budget," it said.

"Just months before the Arab Spring took hold, bin Laden warned affiliates in Yemen and elsewhere that it was too soon to create an Islamic state. The Saudi native, whose family had made its fortune in construction, concluded that there wasn't 'enough steel' in al-Qaeda's regional support structures to warrant even tentative steps toward reestablishing the caliphate," the daily said.

One of bin Laden's principal correspondents Atiyah abd al-Rahman, who served as No. 3 in al-Qaeda before his death, expressed concern over the US drone strikes.

"A 2010 message from Rahman expressed frustration with the CIA-led drone campaign, a source of particular concern because many of his predecessors in the third-ranking slot had been killed in strikes by the unmanned aircraft," it said.

"He was saying in the letter that their guys were getting killed faster than they could be replaced," the US counter-terrorism official was quoted as saying.

Other messages sounded a similar theme. At least two came from the head of al-Qaeda's security unit, a group that had been established to protect against penetrations by informants who might provide targeting tips to the CIA, the daily said.

The unit leader complains 'about having a very low budget, a few thousand dollars', the official said.

"The letter refers to 'ideas' about how to better guard against informants and electronic eavesdropping. But the most obvious solutions, including restricting meetings and movements, would also hamper al-Qaeda's ability to function," the daily said.

Other messages make frequent mention of the organisation's financial hardships, including e-mails in which bin Laden himself complains about the lack of funds.