CAIRO -- Ansar Beit al-Maqdis, a jihadi organization based in the Sinai Peninsula that has carried out several attacks targeting Egyptian security forces, has pledged allegiance to the Islamic State of Iraq and Syria (ISIS).

The news that ISIS had gained followers in Egypt came amid unconfirmed reports that it may have been dealt a serious blow in its heartland of western Iraq. U.S. officials have not confirmed the claims, but Iraqi officials say senior leaders of the group have been killed and its leader, Abu Bakr al-Baghdadi, may have been seriously wounded in U.S. airstrikes in recent days.

On Monday, the Pentagon went so far as to claim that the U.S. airstrike on the 10-vehicle convoy in northern Iraq last week was targeting ISIS "battlefield leaders," but not senior leaders like al-Baghdadi.

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The spokesman, Col. Steve Warren, said Monday that U.S. officials are unable to confirm reports that al-Baghdadi was wounded. An Iraq Interior Ministry intelligence official told The Associated Press on Sunday that an Iraqi airstrike Saturday wounded al-Baghdadi during a meeting in the town of Qaim, near the Syrian border. That would be separate from the U.S. airstrike described by Warren, which happened near Mosul.

Warren said the U.S. is not specifically targeting al-Baghdadi anywhere in Iraq, but it is trying to degrade the group's ability to command its fighting forces.

"What's significant to me is that we hit a military convoy that we knew ISIS leadership was part of," said CBS News contributor Mike Morrell, the former No. 2 at the CIA. "Obviously if we got Baghdadi that's a good thing, but what's really important here is that we found a leadership target and we went after it."

"This was a convoy that we struck that we knew was a leadership convoy, that takes very good intelligence," said Morrell, adding that the "reason these strikes are so important is that they force the leadership of a terrorist group to focus on their own security rather than conduct their operations. The other reason is that as you remove leaders, over time you get weaker leaders, and that is one of the key ways to degrade a terrorist organization."

Morrell said in spite of those continuing efforts by the U.S. and its allies to attack ISIS in Iraq, it was a "very big deal" that not only Ansar Beit al-Maqdis in Egypt, but another jihadist group in Libya had pledged allegiance to al-Baghdadi's organization.

"It shows the popularity of the group, it shows the spread of its influence, and what you'll see as a result is these groups trying to mimic ISIS... trying to take territory in the weeks and months ahead," said Morrell.

The announcement by Ansar Beit al-Maqdis reflects, as Morrell said, the growing regional appeal of ISIS, an al Qaeda breakaway group that has carved out a self-styled caliphate in Syria and Iraq and demanded the loyalty of the world's Muslims.

The announcement pledging loyalty al-Baghdadi came in an audio speech posted late Sunday on the Egyptian militant group's official Twitter account and a militant website. Last week the group had used the same Twitter account to deny reports saying it had pledged allegiance to al-Baghdadi.

ISIS leader Abu Bakr al-Baghdadi speaks at a mosque in Mosul, Iraq.

The unknown speaker in the recording released Sunday says Ansar Beit al-Maqdis decided to join ISIS, "whose emergence resembles a new dawn raising the banner of monotheism."

The speaker said al-Baghdadi was "chosen by God" to establish a new caliphate after "Muslims suffered decades of humiliation."

"Therefore, we have no alternative but to declare our pledge of allegiance to the caliph... to listen and obey him... and we call on all Muslims to pledge allegiance to him."

The speaker went on to urge Egyptians to rise up against what he called "the tyrant," apparently referring to President Abdel-Fattah el-Sissi, who was elected earlier this year after leading the military overthrow of Islamist President Mohammed Morsi in July 2013 amid massive protests demanding his resignation.

Since then Sinai-based militants have carried out scores of attacks mainly targeting soldiers and police, including a coordinated assault last month on an Egyptian army checkpoint that killed 31 troops.

No known group has claimed responsibility for the attack, which prompted the army to declare a state of emergency in parts of northern Sinai, where radical groups have long tapped into local grievances. The attack also led the army to begin demolishing homes along the Sinai border with the Gaza Strip in order to combat smuggling tunnels.

"What are you waiting for, after your honor has been aggressed upon and your sons' blood has been shed at the hands of this tyrant and his soldiers?" the audio statement said.

In a separate statement posted on its Twitter account, the group said the Egyptian army was bent on emptying the border town of Rafah.

"A whole town is removed from the map and no one stands in the face of this aggression or asks about the fate of its children, women and elderly ones," the statement said.

It said the plan is to turn the border area into army barracks to "protect their masters, the Jews, from the blows of the mujahideen, and to blockade Gaza." It went on to refer to el-Sissi by name as a "loyal guard dog" for Israel.

Neither statement referred to the earlier denial that the group had pledged allegiance to al-Baghdadi.

Egypt has long sought to link the radical Sinai group with Morsi's now-banned Muslim Brotherhood, accusing both of being behind the wave of violence since his ouster.

But the Ansar Beit al-Maqdis statement took a veiled shot at the Brotherhood, saying "peaceful means and infidel democracy are not of any benefit to you."

The Brotherhood, which publicly renounced violence decades ago and has condemned the recent attacks, won a series of elections following the 2011 uprising that toppled long-ruling autocrat Hosni Mubarak. But the Islamist group later alienated many Egyptians, who accused it of monopolizing power.

Iraqi officials on Sunday said al-Baghdadi was wounded in an Iraqi airstrike in the western Anbar province as he was meeting with militants. Pentagon officials said they had no immediate information about such a strike or on Baghdadi being wounded. There has been virtually no comment on the matter on jihadi websites.