WASHINGTON - The CIA kept a safe house in Abbottabad, Pakistan, to conduct surveillance for months on the compound where al Qaeda leader Osama bin Laden was killed, The Washington Post, citing US officials, reported on Thursday.

The safe house was a base of operations for intelligence gathering that used Pakistani informants and other sources to compile a "pattern of life" portrait of the occupants and daily activities at the compound where bin Laden was found, officials told the Post.

The surveillance effort was so extensive after the compound was discovered last August that the CIA sought authority from Congress to reallocate tens of millions of dollars within various agency budgets to fund it, the newspaper reported.

The effort included satellite imagery and efforts to record voices inside the compound, the Post said.

It said the safe house was not used in Monday's raid by US Navy SEALs in which bin Laden was killed, and has since been closed.

"The intelligence work was as complete as it was going to be, and it was the military's turn to finish the target," the Post quoted a US official as saying.