A top official of a major Syrian rebel group acknowledged Friday that he considers himself a member of al Qaida, an admission that undercuts Western hopes that the new Islamic Front would prove to be an acceptable counter to the rising influence of other al Qaida affiliates in Syria.

Abu Khaled al Suri, who is a top figure in the rebel group Ahrar al Sham, made the statement in an Internet posting in which he argued that the Islamic State of Iraq and Syria, another radical rebel group, was not al Qaida’s representative in Syria and was not doing the work of al Qaida’s founder, Osama bin Laden, its current leader, Ayman al Zawahiri, or al Qaida’s late leader in Iraq, Abu Musab al Zarqawi, who was killed by an American missile in 2006.

Ahrar al Sham is one of the most militarily effective groups fighting to topple the regime of President Bashar Assad and is one of the largest groups aligned with the Islamic Front, a coalition of rebel groups that announced its formation in September as a counter to the U.S.-backed Supreme Military Council. Ahrar al Sham’s leader, Hassan Aboud, is the political chief of the Islamic Front.

Some analysts of jihadi organizations said al Suri’s admission makes it likely the United States will move to designate Ahrar al Sham a foreign terrorist organization.

“Suri’s prominence in Ahrar al Sham and his public statement praising Zarqawi and Zawahiri will make it very difficult for the U.S. administration not to designate Ahrar,” said Will McCants, the director of the Brookings Institution’s Project on U.S.-Islamic World Relations and an adjunct professor at Johns Hopkins University. “If Ahrar is designated, it will be hard for (aid groups) to move humanitarian aid through the country since they control large swathes of it. The designation will also put the U.S. at odds with Qatar, Ahrar’s main state sponsor.”

Ahrar al Sham’s conservative philosophy has been well known, but its ties to al Qaida had been unclear until Friday’s statement, which al Suri made through Twitter.

In that statement, al Suri said that ISIS, whose outposts in northern and eastern Syria have been attacked by other rebel groups for the past two weeks, had committed crimes against fellow rebels and Muslims in its attempt to use the Syrian rebellion to form its own radical Islamist state.

The statement cited al Suri’s close relationship with bin Laden and Zawahiri, and said that despite ISIS’ claims to be an al Qaida franchise, bin Laden, Zawahiri and Zarqawi could not be held responsible for ISIS’ crimes or behavior. ISIS has used brutal measures, including beheadings, to enforce its harsh interpretation of Islam in the areas of Syria it dominates, a blood thirst that had earned it the enmity of many Syrians.

Zawahiri had designated al Suri to mediate disputes between ISIS and other rebel groups, including the Nusra Front, another al Qaida affiliate battling in Syria.

Charles Lister, a visiting fellow at the Brookings Institution’s center in Doha, Qatar, called the denunciation of ISIS especially strong because it came from a powerful jihadi voice.

“Abu Khaled’s intriguing history has been known for some time now, but his statement against ISIS was clear and wholly condemnatory,” he said. “A statement by Zawahiri, presumably speaking out against ISIS, must now surely be in the works.”

Lister added that al Suri’s profession of friendship with bin Laden, Zawahiri and Zarqawi, three of the West’s most despised figures, undercuts Ahrar al Sham’s previous claims that it was not affiliated with al Qaida, despite its close working relationship with the Nusra Front, which has long claimed an al Qaida relationship. He noted that Aboud, Ahrar al Sham’s leader, has been interviewed frequently by Al Jazeera, the Qatar-based satellite television network.

“Ahrar al Sham undoubtedly intends to play some role in a potentially post-Assad Syria,” Lister said.