The 60-year-old reportedly believes pulling off his own terror attack in the US will see off rivals plotting to seize the leadership.
Ayman al-Zawahiri, the successor to al-Qaeda's founder Osama bin Laden, on the 10th anniversary of the deadly 9/11 strike has ordered an attack to "cement his control" over the terror outfit, a media report said.
The 60-year-old reportedly believes pulling off his own terror attack in the US will see off rivals plotting to seize the leadership, The Sun said.
New York and Washington have been put on maximum alert after intelligence experts uncovered a truck bomb threat.
Janice Fedarcyk of the FBI said: "Al-Qaeda has shown an interest in important dates and anniversaries. In this instance, it is accurate that there is credible, specific but unconfirmed information."
A former Egyptian surgeon, al-Zawahiri was bin Laden's loyal deputy and considered the mastermind behind al-Qaeda.
He took over the terror outfit after bin Laden was killed by US Navy Seals at his Pakistan hideout in May.
Unnamed US officials have confirmed that al-Zawahiri was behind the current alert.
The information said vehicles could be used to blow up bridges and tunnels as the US prepares to honour the 3,000 killed in 2001 with programmes at New York, Washington and Pennsylvania.