The Tripoli-based GNA presidential council has ordered the military prosecutor's office to issue arrest warrants against Haftar and any allies participating in the advance on the city, al-Jazeera has reported.
According to the news network, council chairman Prime Minister Fayez al-Sarraj instructed prosecutors to prepare arrest warrants against the military leader. Earlier, al-Sarraj vowed that Haftar and members of the Libyan National Army would be brought before Libyan and international courts for trial.
The LNA has been advancing into western Libya in recent months, taking control of strategic oil fields and population centres.
Libya collapsed into anarchy with no functioning government following a NATO-led campaign of airstrikes in support of rebels seeking to topple the government of long-time Libyan leader Muammar Gaddafi in 2011. The turmoil led to the rise of competing militia groups and terrorist militants, with these groups establishing control over wide swathes of the country. The largest groups formed two separate governments — the eastern Tobruk-based government, supported by the LNA, and the western UN-backed GNA, based in Tripoli.