Washington: American intelligence agency (CIA) on Friday said that Osama bin Laden’s death marks the greatest victory for US.

"It is a major and essential step in bringing about the terrorist organisation's eventual dissolution," said the Central Intelligence Agency (CIA).

"Although al-Qaeda may not fragment immediately, the loss of bin Laden puts the deadly organisation on a path of decline that will be difficult to reverse," it asserted.

Bin Laden was al-Qaeda's founder and only 'amir' or commander in its 22-year history.

He was largely responsible for the organisation's mystique, its ability to raise money and attract new recruits, and its focus on the US as a target for terrorist attacks. As the only al-Qaeda leader whose authority was universally respected, he also maintained the group's cohesion, it said.

The CIA said in the early morning hours of May 2 in Pakistan, a US military raid of an al-Qaeda compound in Abbottabad killed America's most wanted terrorist Osama bin

The mission's success was the culmination of many years of complex, thorough, and highly-advanced intelligence operations and analysis led by the CIA with support from partners across the Intelligence community.

US agencies had been collecting intelligence about the compound since it was discovered in August, 2010. Multiple streams of intelligence led to the assessment that Bin Laden was hiding there, protected by two of his closest facilitators, it said.