Dozens of Pro-Haftar forces captured amid advance on Libya capital

Forces loyal to Libya's UN-backed government have captured dozens of troops allied to rogue General Khalifa Haftar as they attempted to advance on the capital Tripoli.

The forces said on Friday that the pro-Haftar soldiers were captured as they were pushed back from a key checkpoint less than 30 kilometres from Tripoli.

They posted footage and images online purporting to show the captured troops huddled in a building and in the open.

Security sources have confirmed the capture to pan-Arab broadcaster Al Jazeera.

A correspondent for The New Arab in the capital said "the atmosphere is currently calm" despite the nearby clashes.

News of the capture comes after Haftar ordered his troops to "advance" on the capital Tripoli on Thursday, the seat of the country's internationally-recognised unity government.

"The time has come. Tripoli we are coming," Haftar said in an audio message released online by his self-proclaimed Libyan National Army.

But militiamen from the coastal town of Zawiya, west of Tripoli, pushed back the offensive on Friday, after a "short exchange of fire", a source said on condition of anonymity.

The Tripoli-based government had previously said that security forces in the capital were on "high alert" while condemning the threats of an armed showdown.

Abdel Razzaq, a shopkeeper in the city, said that panicked locals flooded his store on Thursday but that business had returned to usual on Friday.

"I don't think that there is total calm – there is fear that war will return," he added.

Haftar's forces have emerged as a key player, opposing the government in Tripoli and backing a parallel administration in the east.

The rise in tensions comes as UN Secretary-General Antonio Guterres visited Tripoli ahead of a planned conference later this month to hammer out a roadmap for delayed parliamentary and presidential elections.

"I am deeply concerned by the military movement taking place in Libya and the risk of confrontation," Guterres tweeted from the capital.

"There is no military solution" to Libya's woes, he added.

The militia is one of dozens that have proliferated since the overthrow of veteran dictator Muammar Gaddafi in a NATO-backed uprising in 2011 and are variously aligned with the UN-backed unity government in the capital and a rival administration in the east backed by Haftar's forces.