Libya's UN-backed Government of National Accord (GNA) in Tripoli declared a state of emergency and mobilization in the north-central city of Sirte.
The decision came after forces of east Libya-based commander Khalifa Haftar, known as the Libyan National Army, reportedly move forward to the southern outskirt of the city.
All troops of the militia connected to the UN-backed unity government were called to duty, said a statement from the security and protection force in Sirte, affiliated to the GNA.
“Any attack on the city will mean a declaration of war and its consequences will turn into a disaster,” said the statement, adding that Haftar’s forces took provocative steps recurrently.
Meanwhile, some activist posted videos on social media showing armed men loyal to Haftar patrolling at the southern gate of the city.
Libya has remained dogged by turmoil since 2011 when a bloody NATO-backed uprising led to the death of longstanding leader Muammar Gaddafi after four decades in power.
Since then, Libya’s stark political divisions have yielded two rival seats of power -- one in Tobruk (to which Haftar is affiliated) and another in Tripoli -- and a host of heavily-armed militia groups.