The so called 'Al-Borra Battalion' sent out a video on Monday, claiming the attack on Lebanon’s northern village of Al-Qasr from Syria’s al-Qusair in Homs Province.
Al-Nusra Front has claimed responsibility for most of the fatal bombings targeting civilians and government institutions across Syria after the outbreak of the country's unrest in early 2011.
Abu Baker al-Baghdadi, leader of al-Qaida in Iraq, declared the merger with al-Nusra Front, two days after al-Qaida's central leader Ayman al-Zawahiri urged unification of terrorists in Syria.
Syria has asked the UN Security Council to list the radical al-Nusra Front as a terrorist group. The Syrian Foreign Ministry said in a statement that the recent merger had proven Syrian government's previous claims about the armed rebel groups being in connection with al-Qaida.
Saudi Arabia, Qatar and Turkey are accused by the Syrian government for orchestrating the deadly chaos which has left thousands of people dead.