The special forces of the Islamic State (IS) militants killed 50 rival rebels in an operation in the northern province of Aleppo on Tuesday, the IS said in an online statement.The IS Special Forces, known as "Enghimasiyoun" Arabic for "those who immerse themselves," infiltrated a position held by rival rebel groups from the tribe of Shuaitat in the town of Mare' in the northern countryside of Aleppo, killing 50 of them, the IS statement said, adding that the targeted tribesmen fled the eastern province of Deir al-Zour to Mare', Xinhua reported.It added that the Enghimasiyoun also infiltrated another position of the rival rebels, blowing their explosive belts, and killing tens of them.The IS said its special forces targeted the so-called Sahwat, or the Awakening groups, which are anti-IS militants.Mare' is considered one of the most strategic rebel position in northern Syria. The IS has been trying to storm the town for months due to its strategic location near the Turkish borders and to cut off the rebel supply lines in northern Aleppo.