A new generation of al Qaeda leaders has emerged under Osama bin Laden to cement control over the network's operations, The New York Times reported Monday.

The new leaders rose from within the organization after the death or capture of the operatives that built al Qaeda before the Sept. 11, 2001, attacks, leading to surprise and dismay within United States intelligence agencies at the group's ability to rebound from an American-led offensive, the report said, citing American intelligence and counter-terrorism officials.

American officials have been focusing on a band of al Qaeda training camps in Pakistan's remote mountains, but a clearer picture is emerging about those who are running the camps and thought to be involved in plotting attacks, the report said.

American, European and Pakistani authorities have for months been piecing together a picture of the new leadership, based in part on evidence-gathering during terrorism investigations in the past two years.

Intelligence officials have also learned new information about al Qaeda's structure through intercepted communications between operatives in Pakistan's tribal areas, although officials said the group has a complex network of human couriers to evade electronic eavesdropping.

The investigation into the plot to destroy multiple commercial airlines after takeoff from London last year has led officials to conclude that an Egyptian paramilitary commander called Abu Ubaidah al-Masri was the al Qaeda operative in Pakistan orchestrating the attack, officials said.

Masri, a veteran of the wars in Afghanistan, is believed to travel frequently over the rugged border between Pakistan and Afghanistan, and emerged as one of al Qaeda's senior operatives after the death of Abu Hamza Rabia, another Egyptian who was killed in a missile strike in Pakistan in 2005, according to the report.