Intelcenter / AFP - Getty Images file

Al-Qaida leader Ayman al-Zawahiri speaks in a video released by al-Qaida's media arm as-Sahab on March 16.

Editor's note: A correction had been made to this article. Click here to view it:

Fugitive al-Qaida leader Ayman Al-Zawahiri has released a new audio message about Yemen at a time of escalating fighting in the country that one Yemeni official on Tuesday described as "all-out war."

The release of the audio comes just two days after White House counterterrorism adviser John Brennan visited the Yemeni capital of Sanaa to meet with its new president, Abed Rabbo Mansour Hadi, to discuss ramping up the battle against al-Qaida affiliated militants who now control large swaths of the country's southern region.

While there is still no public translation of the new Zawahiri audio message, a U.S. government official familiar with the contents tells NBC News it was clearly recorded before the news broke last week about a foiled plot to blow up a U.S. airliner with more-sophisticated underwear bomb.

The message discusses the transition from exiled former Yemeni president Ali Abdullah Saleh to Hadi, said the official, speaking on condition of anonymity.

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NBC News terror analyst Evan Kohlmann notes that there is typically a two- to three-week lapse between the events described in Zawahiri’s messages and their public release.  (Kohlmann's Flashpoint Intel service is working to translate the message, but he gives the title as, "Yemen: Between a Fugitive Puppet and a Collaborating Stooge," apparent references to Saleh and Hadi.)

Read more reporting by Michael Isikoff in the 'Isikoff Files'

Over the past week and a half, Yemeni forces -- backed by U.S. military trainers and drone strikes -- have dramatically escalated their attacks on al-Qaida militants in the south.

A Yemen government official estimated as many as 20,000 troops were now involved in the battle, supported by approximately 50 to 60 U.S. trainers.

"We have begun to reintroduce small numbers of trainers into Yemen," a Pentagon spokesman, a Navy Capt. John Kirby, told reporters this week. 

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