WASHINGTON - The Pentagon said yesterday that it had taken custody of one of al-Qaeda's most senior members, an operational commander who had been active in Afghanistan and Pakistan.

Defense Department and U.S. intelligence officials would not say precisely when or where Abdul Hadi al-Iraqi was captured, or by whom, only that he was headed for his home country of Iraq when detained. Officials said Iraqi was handed over to the CIA in late 2006 and has been providing critically important information about al-Qaeda.

"This was a very important capture," said Army Col. Gary L. Keck, a Pentagon spokesman. "He was one of al-Qaeda's highest-ranking and experienced senior operatives. He had been one of the organization's key paramilitary commanders in Afghanistan, and we know he was in direct communication" with al-Qaeda's second-in-command, Ayman al-Zawahiri and perhaps Osama bin Laden.

Officials did not disclose where the CIA had held Iraqi since he was captured or why he was being transferred to the U.S. detention center for terrorism suspects at Guantanamo Bay, Cuba.

In a declassified summary, the Pentagon accused Iraqi of launching attacks on U.S. and coalition forces from Pakistan and of leading an effort to assassinate Pakistan's president, Pervez Musharraf, as well as unspecified officials of the United Nations.

The summary said Iraqi was trying to get back into Iraq to manage al-Qaeda's affairs there "and possibly focus on operations outside Iraq against Western targets." Iraqi had met with al-Qaeda members in Iran, and he "believed that they should be doing more with the fight, including supporting efforts in Iraq and causing problems within Iran," the Pentagon summary said.

Iraqi, who was born in Mosul, Iraq, in 1961, was transferred from CIA custody to the Pentagon this week. The handover occurred at Guantanamo, where Iraqi joins 14 other accused al-Qaeda leaders whose cases are being reviewed by military commissions to determine whether they should face a tribunal. The Pentagon said in a statement that Iraqi was expected to undergo a similar proceeding, given his alleged stature within al-Qaeda.

A U.S. counterterrorism official said Iraqi had been providing crucial information on al-Qaeda's command structure and its operations, including continuing efforts to launch attacks around the world with help from senior leaders in the Afghanistan-Pakistan region. That official spoke on the condition of anonymity, saying he could not discuss the details of Iraqi's arrest or the cooperation between the United States and at least one U.S. ally that participated in his capture.

"This is sensitive. It would put key foreign partners at risk were we to disclose where he was captured," said the U.S. counterterrorism official, who added that "the CIA was deeply involved in efforts to locate and capture this individual."