Al Qaeda leader Ayman al-Zawahiri is reportedly suffering from a potentially debilitating heart condition and may be in poor health.

A senior counterterrorism official told CNN that the U.S. believes Zawahiri may be suffering from a potentially serious condition, while cautioning that it was unclear how it would affect the terror group’s leadership now or in the future.

{mosads}The official’s comments follow a U.N. report this summer that stated that the “health and longevity of [Al Qaeda’s] leader … and how the succession will work are in doubt,” according to CNN.

News of Zawahiri’s ailing health follows reports Wednesday indicating that Hamza bin Laden, the son of former al Qaeda leader Osama bin Laden who himself had been tapped to lead the group in the future, had been killed.

Three U.S. officials confirmed to NBC News that the U.S. believes the younger bin Laden is dead but would not give any further information Wednesday.

Osama bin Laden, leader of the terror group during the 2000s and in particular for the 9/11 attacks, was killed in 2011 by a Navy SEAL raid.