TRIPOLI, Aug. 23 (Xinhua) -- Libya's UN-backed government on Thursday declared a high state of security alert shortly after a deadly attack by Islamic State (IS) militants on a security checkpoint in the western city of Zliten.

The government "declares state of security alert and raises the maximum readiness and caution between all its security services," the interior ministry said.

The ministry also called on people to "cooperate with the security personnel and report any suspicious acts or security violations."

Earlier in the day, IS-linked militants riding a four-wheel drive vehicle attacked a security checkpoint in Zliten, some 160 km east of the capital Tripoli, killing seven security personnel and injuring two others, a local security source told Xinhua.

The attack came less than a day after IS leader Abu Bakr al-Baghdadi reportedly issued an audio tape calling on his supporters to "turn to Libya and support the Mujahideen in Libya, Syria and Iraq."

The interior ministry assured that the security between the cities of Zliten and al-Khoms is under control, while the highway linking the two cities will be reopened as soon as security measures are in place.