BEIRUT -- The Syrian army and its allies have launched a counteroffensive to recapture a village south of the city of Aleppo that was overrun by al Qaeda-allied militant a few days earlier, activists said Wednesday.

The development came as Syria's al Qaeda branch, known as the Nusra Front, confirmed on Wednesday the death of Abu Firas al-Souri, a senior figure in the group, in a U.S. airstrike in the northern province of Idlib on Sunday.

Syrian activist groups said the push near Aleppo, which started late Tuesday night, is aimed at retaking the village of Tel al-Ais, which overlooks the Damascus-Aleppo highway. The village was captured on Monday by rebels allied with al Qaeda's affiliate in Syria, the Nusra Front.

The fighting outside Aleppo, the country's second-largest city, has been the worst since a partial cease-fire agreement came into effect in late February and has threatened to completely derail the agreement, which greatly reduced overall violence in Syria.

The fighting pits Syrian government forces and allied Lebanese Hezbollah militiamen against militants, including the Nusra Front. The al Qaeda branch is excluded from the truce along with its rival the Islamic State group.

Meanwhile, the SITE Intelligence Group, which monitors militant websites said the Nusra Front posted on social media Wednesday a statement in which it accused the U.S. of "blatantly" helping the Syrian government with the airstrike that killed Abu Firas al-Souri in the northern province of Idlib.

The al Qaeda branch announced that a "group from the best of the mujahideen," including Abu Firas, was killed in an airstrike by the "Crusader-Arab coalition" led by the United States that targeted a training camp that was about to "graduate a class of mujahideen."

Pentagon press secretary Peter Cook said Monday that the U.S. carried out an airstrike late Sunday on a senior al Qaeda "operational meeting" in northwest Syria that resulted in "several enemy killed." He said at the time the U.S. believes al-Souri was at the meeting.