ABBOTTABAD, Pakistan – Pakistan's president denied suggestions his country's security forces may have sheltered Osama bin Laden before he was killed by American forces, and said their cooperation with the United States helped pinpoint the world's most wanted man.

Asif Ali Zardari said, however, that Monday's operation against bin Laden was not conducted with Pakistani forces — confirming accounts by US officials that Islamabad was not involved in the raid. Zardari did not refer to American accounts that Pakistan was not told about the operation until it was over.

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His comments in a Washington Post opinion piece Monday were Pakistan's first formal response to the suspicions by US lawmakers and other critics.

Bin Laden was killed in a large house close to a military academy in the bustling northwestern town of Abbottabad, not in the remote Afghan border region where many had assumed he had been holed up. That was quickly taken as a sign of possible collusion with the country's powerful security establishment, which Western officials have long regarded with a measure of suspicion despite several notable al-Qaida arrests in the country since 2001.

"Some in the US press have suggested that Pakistan lacked vitality in its pursuit of terrorism, or worse yet that we were disingenuous and actually protected the terrorists we claimed to be pursuing. Such baseless speculation may make exciting cable news, but it doesn't reflect fact," Zardari wrote.

US Senate Armed Services Committee Chairman Carl Levin said Pakistan's intelligence and army have "got a lot of explaining to do," given that bin Laden was holed up in such a large house with surrounding buildings, the fact that its residents took the unusual step of burning their garbage and avoiding any trash collection.

"It's hard to imagine that the military or police did not have any ideas what was going on inside of that," Levin said.

Suspicions were also aired in many Pakistan's media and on the street Tuesday.

"That house was obviously a suspicious one," said Jahangir Khan, who was buying a newspaper in Abbottabad. "Either it was a complete failure of our intelligence agencies or they were involved in this affair."

US officials have said that Pakistani officials were not told about the early morning helicopter raid until the strike team had killed bin Laden had returned to Afghanistan from where they took off from, citing security reasons.

Many Pakistanis were surprised at how this was possible, especially when initial reports stated that the choppers took off from a Pakistani air base. Some were angry that the country's sovereignty had been violated — an especially sensitive issue given the unpopularity of America here.

Zardari said it "was not a joint operation" — the kind of which has been conducted in the past against lesser terror suspects in Pakistan — but that Pakistani cooperation, in a general sense, had helped lead them to bin Laden.

"A decade of cooperation and partnership between the United States and Pakistan led up to the elimination of Osama bin Laden as a continuing threat to the civilized world," he said.

President Barack Obama also said the country's anti-terror alliance had helped in the run-up to the operation, but did not thank Pakistan when he announced the death of bin Laden.

The death of bin Laden has raised fears of revenge attacks, both in Pakistan — which has seen hundreds of suicide attacks by al-Qaida and its allies since 2007 — and internationally. The US Embassy said its missions in Pakistan would remain closed to the public until further notice.