The Syrian army managed to break the three-year siege by the Islamic State terror group of a government-controlled military base in eastern Syria, according to official sources and activists.

Following combat with IS fighters on Tuesday, the pro-government forces were able to breach the encirclement and open corridors to reach the base of the army’s 137th Brigade in the city of Deir al-Zour, the Syrian Observatory for Human Rights and the state news agency SANA reported.

Deir al-Zour city is located 450 km to the northeast of Damascus on the banks of the Euphrates River.

SOHR, a Britain-based war monitor, added that the advance of troops loyal to the Syrian government took place after they removed mines and explosive devices from the area that separated them from the besieged barracks.

According to SANA, the inhabitants of the government-controlled neighbourhoods of Deir al-Zour celebrated the arrival of the troops to break the siege.

The offensive against IS combatants in the province of Deir al-Zour, mostly controlled by the extremists, began on Saturday on two fronts and was launched from the neighbouring province of Homs, with the support of Syrian artillery and aviation, Efe news reported.

Despite the IS siege of Deir al-Zour since early 2015, the Syrian army maintained control of several neighbourhoods in the northwest of the city and the military airport, located in the southeast, in addition to the aforementioned barracks.

The province of Deir al-Zour is the last main bastion of IS militants in Syria.