US monitoring groups said the death of Yazid, who was the leader of al Qaeda in Afghanistan and its liaison with the Taliban for three years, was announced by the group in a message to jihadist websites on Monday.
The White House said his apparent death in Pakistan in a US drone strike was "unquestionably a severe blow" to the global terror network.
Yazid, one of a number of Egyptians in the higher echelons of al Qaeda, was a founding member of the network and once top money man to bin Laden who was accused of channelling cash to some of the September 11 hijackers.
Yazid, also known as Sheikh Said al Masri, would be one of the highest-profile al Qaeda leaders killed since US President Barack Obama took office.
"We welcome his demise," White House spokesman Robert Gibbs said, after a Pakistani security official said there was "reason to believe" Yazid was dead, probably killed in a drone attack in North Waziristan in late May.
Gibbs said he had spoken to Obama's top counter-terror official John Brennan who told him Yazid, al Qaeda's finance specialist, was "the biggest target to be either killed or captured in five years."
The United States has been waging a covert drone war against militants in Pakistan's tribal areas on the Afghan border, which Washington has declared a headquarters of al Qaeda and the most dangerous place on Earth.
A US official had earlier said that there was "strong reason" to believe Yazid had been killed in the tribal areas.
"Al Masri was the group's chief operating officer, with a hand in everything from finances to operational planning," the US official said.
"He was also the organisation's prime conduit to bin Laden and (al Qaeda number two Ayman) Zawahiri," he said.
"He was key to al Qaeda's command and control." The al Qaeda message carried by the SITE group that monitors websites did not say where or when Yazid was killed other than to speak of his "martyrdom".
But it said his wife, three of his daughters, his granddaughter, and other men, women and children were killed along with him.
"His death will only be a severe curse by his life upon the infidels. The response is near," according to the message translated by SITE.
The Pakistani security official told AFP there was "reason to believe" Yazid was dead based on electronic intercepts, telephone intercepts and human intelligence, but that without a body there was no 100 percent confirmation.
Rahimullah Yusufzai, a prominent Pakistani expert on militant groups, said al Qaeda's announcement showed that there was no longer a safe haven for the terror network in the tribal belt and that US intelligence was improving.
"It has become difficult for them (al Qaeda) to operate independently, they cannot link up with the central leadership and they are not in a position to launch big operations," he told AFP.
Analysts said several of Yazid's predecessors as al Qaeda number three had been killed or captured, while there were rumours in 2008 that he himself had been killed.
Yazid, 54, was among those whose assets were frozen by the US Treasury in the wake of the September 11, 2001 attacks on the United States.
According to the FBI, it was Yazid who transferred funds via Dubai for Mohammed Atta, Marwan al Shehhi and Wal al Shehri, three of the hijackers who flew aircraft into the Twin Towers and the Pentagon.
Yazid, wearing thick glasses and a white turban, appeared in a number of videos released by al Qaeda. A former member of the Islamic Jihad movement in Egypt, he had close links with fellow Egyptian Zawahiri and served time in jail over the 1981 assassination of Egyptian president Anwar Sadat.
"This is one of the most significant blows against al Qaeda in recent years and its impact will be felt by the group," said Ben Venzke of intelligence analysis group IntelCenter. He said Yazid ran al Qaeda operations in Afghanistan and Pakistan.
According to Yasser al Sirri, the director of the London-based Islamic Observatory, Yazid was trusted by bin Laden, for whom he ran businesses in Sudan when the founder of al Qaeda lived there in the 1990s.
"Yazid is known for his integrity and management skills, but has never taken organisational or military responsibility at the heart of al Qaeda, of which he was one of the founders in 1989," Sirri said.
Yazid's last public statement was on May 4, when he delivered eulogies for the two top al Qaeda leaders in Iraq who were killed in April.
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