The Syrian army and allied fighters fully captured the city of Mayadeen in the countryside of the eastern province of Deir al-Zour on Saturday, state news agency SANA reported.

Capturing Mayadeen city comes after intense battles with the Islamic State (IS), as the city was one of their last key strongholds in Deir al-Zour near Iraq.

Regarded as the IS capital in Deir al-Zour, the city had served as an important hub for IS between the city of Bukamal in the remote eastern countryside of Deir al-Zour, on the Iraqi border, and the capital city of Deir al-Zour, where the IS has lost key ground.

The city lies on the eastern bank of the Euphrates River, and the advance of the Syrian army in that area helped in tightening the siege on the IS militants in the few neighborhoods they are still holding inside Deir al-Zour city.

The Syrian army has managed to advance against IS in Deir al-Zour with the help of Iranian-backed fighters and the airstrikes and special forces of Russia.

Last month, the army broke IS three-year siege on Deir al-Zour, capturing 75 percent of the capital city and continuing to attack the IS positions in the countryside of that key oil-rich province.

This comes amid reports that IS has almost lost its de facto capital in Raqqa as a result of the progress achieved by the U.S.-backed Syrian Democratic Forces.

The terror group is now holding the city of Bukamal, the last key stronghold in Deir al-Zour, and its defeat in that area would be the final countdown for its eradication from Syria.