Libya's Islamist-backed government in the capital, Tripoli, has declared a state of emergency after reports that four members of the rival United Nations' unity government have arrived.

In a statement, the so-called National Salvation government in Tripoli said Thursday that it tasked the Defense Ministry, militias and security apparatus to "increase security patrols and checkpoints."

The Tripoli government — one of Libya's three governments and which is backed by militias — has warned before of the United Nations' attempts to install a government in the capital.

The west has pinned hope for resolving Libya's chaos and blocking the Islamic State group's growth there on the unity government, which is brokered by the United Nations and headed by Fayez Serraj, who is yet to enter the capital later this month.