(CNN) Syrian regime forces have broken a three-year ISIS siege of the eastern city of Deir Ezzor, Syria's official news agency SANA reported.

Quoting a reporter on the ground, SANA said "advancing forces coming from the western front met guards of Regiment 137 on Tuesday afternoon, and thus, broke the siege imposed by ISIS terrorists on the city."

Regiment 137 refers to a group of Syrian regime soldiers who have been trapped in Deir Ezzor for nearly three years.

With ISIS under increasing pressure in Raqqa -- its self-declared caliphate -- the strategic Deir Ezzor had been viewed as the terror group's last major position in Syria.

"Here you are today side by side with your peers who gave everything for your victory and waged the hardest of battles to break the ring around the city," SANA quoted President Bashar al-Assad as telling Syrian soldiers.

Read More