BEIRUT -- A media outlet linked to the Syrian military said Friday that the leader of Islamic State of Iraq and Syria (ISIS), Abu Bakr al-Baghdadi, may be holed up in an ISIS pocket in the eastern town of Boukamal, which government forces and their allies recaptured this week before losing parts of it later.

The claim was denied by Syrian opposition activists who said the government is trying to make up for losses it suffered in Boukamal when large parts were retaken by the extremists again on Friday.

Officials told CBS News correspondent David Martin they have not tracked any signs that al-Baghdadi has been killed or captured.

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The whereabouts of al-Baghdadi are not known and if he is killed or captured it would be another blow for the organization that has lost more than 90 percent of lands it once controlled in Iraq and Syria where the group declared a caliphate in June 2014.

Al-Baghdadi's whereabouts and the question of whether he is dead or alive have been a continuing source of mystery and confusion.

The Syrian Central Military Media said that, as Syrian troops and their allies conducted search operations in Boukamal, they "got the information" that Abu Bakr al-Baghdadi might be "in one of the pockets" in the town. The report did not elaborate on how the soldiers heard about al-Baghdadi or what they were doing about the information.

Rami Abdurrahman, who heads the Britain-based Syrian Observatory for Human Rights monitoring group, and Omar Abu Laila, a Europe-based opposition activist originally from Syria's eastern province of Deir el-Zour both denied the report that al-Baghdadi is in Boukamal.

Boukamal, ISIS' last major stronghold in Syria, was taken on Thursday after ISIS militants withdrew from it. Abdurrahman said IS launched a counteroffensive on Boukamal capturing more than 40 percent of the town, mostly its northern neighborhoods.

"The fighting is ongoing, now close to the town's center," Abdurrahman said, adding that when ISIS fighters withdrew from Boukamal on Thursday it was a trap they set to hit back at government forces and their allies.

Abu Laila said ISIS fighters control most of Boukamal adding that government claims that al-Baghdadi is in the town is to cover for their losses.

In September, al-Baghdadi released an audio in which he urged his followers to burn their enemies everywhere and target "media centers of the infidels." It was his first purported audio in nearly a year.

"Intensify your strikes, one after the next ... and make the media centers of the infidels and their intellectual battlefields amongst your targets," Baghdadi purportedly said. "Keep up your jihad and blessed operations ... and don't let the crusaders and the apostates enjoy peace and tranquility in their own homes while your brethren endure the bombardment, the killing and destruction."

Al-Baghdadi has only appeared in public once in 2014 in the northern Iraqi city of Mosul.

Russian officials said in June there was a "high probability" that al-Baghdadi was killed in a Russian airstrike on the outskirts of the Syrian city of Raqqa, the group's de facto capital that the extremists lost last month. U.S. officials later said they believed he was still alive.

Al-Baghdadi's whereabouts are unknown but he is believed to be in IS' dwindling territory in eastern Syria. Opposition activists say he is also likely somewhere in the wide desert that stretches toward Iraq.