The Latest on developments in Libya (all times local):

5:30 p.m.

Libyan army commander Khalifa Hifter in an audio recording posted online has ordered his forces to march to Tripoli, the capital of the U.N.-backed government.

Hifter, who commands the so-called Libya National Army based in the east, described his forces' move as a "victorious march" to "shake the lands under the feet of the unjust bunch."

He ordered forces not to open fire on any civilians saying, "whoever raises the white banner is safe."

His forces have taken over the town of Gharyan, 50 kilometers (31 miles) from Tripoli.

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10:15 a.m.

The U.N. chief says he's worried about a major armed showdown in Libya and is urging warring factions to instead turn to dialogue.

Antonio Guterres' remarks came as Libyan forces loyal to strongman Khalifa Hifter entered the town of Gharyan, about 50 kilometers, or 31 miles, south of the capital. It's the closest to Tripoli that Hifter's fighters reached in their campaign westwards from the country's east.

Guterres posted on Twitter on Thursday that he's "deeply concerned by the military movement taking place in Libya and the risk of confrontation."

He added: "There is no military solution. Only intra-Libyan dialogue can solve Libyan problems."

Guterres arrived in Libya on Wednesday — the first U.N. chief to visit since the 2011 uprising that toppled and later killed long-time ruler Moammar Gadhafi.