Pakistan's main intelligence agency, the ISI, has said it is embarrassed by its failures on al-Qaeda leader Osama Bin Laden.
An ISI official told the BBC the compound in Abbottabad where Bin Laden was killed by US forces on Sunday had been raided several years ago.
But the compound "was not on our radar" since then, the official said.
The government of Pakistan has categorically denied any knowledge of the raid before it took place.
No base within Pakistan was used by US forces, the ministry of foreign affairs said in a statement.
It went on: "US helicopters entered Pakistani airspace making use of blind spots in the radar coverage due to hilly terrain."
However, the ministry defended the ISI, saying: "As far as the target compound is concerned, ISI had been sharing information with CIA and other friendly intelligence agencies since 2009."
'Caught by surprise'
Bin Laden, 54, was the founder and leader of al-Qaeda. He is believed to have ordered the attacks on New York and Washington on 11 September 2001, as well as a number of other deadly bombings.
The ISI official gave new details of the raid, saying Bin Laden's young daughter had said she saw her father shot.
He told the BBC's Owen Bennett-Jones in Islamabad that the compound in Abbottabad, just 100km (62 miles) from the capital, was raided when under construction in 2003.
It was believed an al-Qaeda operative, Abu Faraj al-Libi, was there.
But since then, "the compound was not on our radar, it is an embarrassment for the ISI", the official said. "We're good, but we're not God."
He added: "This one failure should not make us look totally incompetent. Look at our track record. For the last 10 years, we have captured Taliban and al-Qaeda in their hundreds - more than any other countries put together."
The compound is about a kilometre from the Pakistan Military Academy - the country's equivalent of West Point or Sandhurst.
The ISI official also gave new or differing accounts of some of the events of Sunday's raid. They included:
- There were 17-18 people in the compound at the time of the attack
- The Americans took away one person still alive, possibly a Bin Laden son
- Those who survived the attack included a wife, a daughter and eight to nine other children, not apparently Bin Laden's; all had their hands tied by the Americans
- The surviving Yemeni wife said they had moved to the compound a few months ago
- Bin Laden's daughter, aged 12 or 13, saw her father shot
The official said it was thought the Americans wanted to take away the surviving women and children but had to abandon the plan when one of the helicopters malfunctioned.
The helicopter was destroyed by the special forces unit.
The US has not commented on anyone it captured or had planned to capture, other than saying it had taken Bin Laden's body.
The ISI official said the organisation had recovered some documents from the compound.
The CIA is already said to be going through a large number of hard drives and storage devices seized in the raid.
The White House has not disclosed whether anyone has claimed the $25m (£15m) reward for leading the US to Bin Laden.
White House counter-terrorism adviser John Brennan said there had been concern Pakistani forces would deploy to counter the US Navy Seal team conducting the raid but it had avoided any confrontation.
The ISI official said: "We were totally caught by surprise. They were in and out before we could react."
Our correspondent says residents near the compound in Abbottabad reported that Pakistani soldiers had asked them to switch off their lights an hour before the attack, but the ISI official said this was not true and that it had no advance knowledge of the raid.
Earlier, in an opinion piece in the Washington Post, President Asif Ali Zardari admitted Bin Laden "was not anywhere we had anticipated he would be".
But he denied the killing suggested Pakistan was failing in its efforts to tackle terrorism.
Mr Zardari said Pakistan had "never been and never will be the hotbed of fanaticism that is often described by the media".
"Such baseless speculation may make exciting cable news, but it doesn't reflect fact," he said.
"Pakistan had as much reason to despise al-Qaeda as any nation. The war on terrorism is as much Pakistan's war as it is America's."
Mr Brennan had said it was "inconceivable that Bin Laden did not have a support system" in Pakistan. He estimated Bin Laden had been living in the compound in Abbottabad for five or six years.
Pakistani Foreign Secretary Salman Bashir tried to draw a line under the matter, saying: "Who did what is beside the point... This issue of Osama Bin Laden is history."
Bin Laden was America's most wanted man but had eluded capture for more than a decade.
US officials say that after DNA tests they are "99.9%" sure that the man they shot and killed and later buried at sea was Bin Laden.
US President Barack Obama watched the entire operation in real time in the White House with his national security team.
Mr Brennan said: "The minutes passed like days."
CIA director Leon Panetta narrated via a video screen from a separate Washington office, with Bin Laden given the code name Geronimo.
Mr Panetta's narration lasted several minutes. "They've reached the target... We have a visual on Geronimo... Geronimo EKIA (enemy killed in action)."
Mr Obama said: "We got him."
Bin Laden, his son Khalid, trusted personal courier Sheikh Abu Ahmed and the courier's brother were all killed, along with an unidentified woman.
Bin Laden was shot above his left eye, blowing away a section of his skull, and was also shot in the chest.
The BBC's Andrew North in Washington says the White House is still discussing whether to release a video that was made of Bin Laden's burial from an aircraft carrier in the Arabian Sea, which some Islamic scholars have said did not conform with tradition.
Our correspondent says many people will want proof that Bin Laden is dead but the White House will be concerned about the reaction if the video, and still photographs of the body, are released.