There is no truth to a CBS News report that Al Qaeda’s second in command, Ayman al-Zawahiri, is injured or dead, sources tell FOX News.

A local Taliban official, as well as an intelligence official in South Waziristan, told FOX News that the report, based on a purported letter from a Taliban leader, is baseless.

CBS News said it obtained a copy of the letter from sources in Pakistan, where Zawahiri, second only to Usama bin Laden, is thought to be hiding.

The letter, dated Tuesday and purportedly from Taliban leader Baitullah Mehsud, said Zawahiri is in "severe pain" and his "injuries are infected."

"We deny it categorically," Mehsud spokesman Maulvi Umar told The Associated Press by telephone from an undisclosed location inside Pakistan.

A missile strike Monday in Pakistan’s tribal areas reportedly killed Al Qaeda operative Abu Khabab al-Masri, considered a "Top Ten" target as the terrorist organization’s top expert on chemical and biological weapons.

That strike also killed five others, though it isn’t clear whether Zawahiri was at the scene or even in the area.

Click here to read the CBS News report.

The Associated Press contributed to this report.