A picture shows weapons reportedly seized by Syrian government forces during a military operation against Islamic State (IS) group jihadists. (file pic)

DAMASCUS, Nov. 10 (Xinhua) -- The Islamic State (IS) clawed back over 40 percent of the city of al-Bukamal, the last IS stronghold that has been recently captured by the Syrian government forces, a monitor group reported on Friday.

Following the Syrian army's declaration of capturing al-Bukamal in the eastern countryside of Deir al-Zour province in eastern Syria on Thursday, the IS militants unleashed a wide-scale counteroffensive on the city, capturing over 40 percent of it, said the Syrian Observatory for Human Rights.

The terror-designated militants recaptured neighborhoods in the northern and northeastern as well as the northwestern parts of the city, the UK-based watchdog group said, adding the Syrian forces' control in the city shrunk to the southern, southwestern and the southeastern parts of the city.

Now, intense battles are raging between the IS militants and the Syrian government forces and allied troops in al-Bukamal, the last IS stronghold in Syria near Iraq.

Being their last home in Syria explains why the IS militants are fighting back.

Additionally, the media wing of the Lebanese Hezbollah group, which is fighting alongside the Syrian army in Deir al-Zour, said they had information that the leader of IS, Abu Baker al-Baghdadi, is hiding in the city, which could be another reason why the IS militants are feverishly trying to take hold of al-Bukamal.

On Thursday, the Syrian army declared capturing the city, saying in a statement that the liberation of al-Bukamal constitutes a "strategic achievement and a base for eradicating remnants of the terrorist organizations with its various names along the Syrian territories."

"The liberation of the city is of great importance since it represents an announcement of the fall of IS terrorist organization project in the region, in general, and a collapse of the illusions of its sponsors and supporters to divide Syria," the statement said.

The army also hailed what it described as "the continuous coordination" between the Syrian and Iraqi armies," saying it has played a big role in clearing large swathes of the border area and in preventing the infiltration of IS militants across the border.

Al-Bukamal is very important for IS due to its proximity to IS-held areas on the Iraqi side of the border, which have recently been stormed by the Iraqi army and allied troops.

Last month, the U.S.-backed Syrian Democratic Forces captured the northern city of Raqqa, the de facto capital of IS.

Also, the Syrian army captured the capital city of Deir al-Zour this month.