Pro-Haftar militia forces reach outskirts of Tripoli

Forces loyal to Libyan strongman Khalifa Haftar reached a security barrier within 30 kilometres (19 miles) from the capital Tripoli late on Thursday, an AFP journalist saw, as world powers warned of consequences for military action.

General Abdessalem al-Hassi, head of operations for Haftar's self-proclaimed Libyan National Army (LNA) in the eastern region, said his forces had seized the roadblock without any fighting.

Haftar's forces announced on Wednesday they were gearing up for an offensive in the west of the country to purge it of "terrorists and mercenaries", having seized key areas of the country's south since the start of the year.

Dozens of uniformed men and a least 15 trucks carrying anti-aircraft guns took up positions at the control point known as "Bridge 27", just 27 kilometres (17 miles) from Tripoli, the seat of the internationally-recognised unity government.

Meanwhile, fighters from the Tripoli Protection Force, an alliance of militias from the capital city, announced on Facebook that they had launched an operation to stop the LNA advance, without giving details.

Unity government chief Fayez al-Sarraj earlier condemned Haftar's "escalation" and said he had ordered loyalist forces to prepare to "face all threats."

"The time has come," Haftar said in an audio message released on Thursday by his self-proclaimed Libyan National Army, pledging to spare civilians and "state institutions."

Dozens of militias have fought for control of the North African country since a NATO-backed uprising toppled and killed longtime dictator Muamer Qadhafi in 2011.

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

On Thursday evening LNA spokesman Ahmed Mesmari announced that the force was "at the gates of the capital".

Unity government chief Fayez al-Sarraj earlier condemned Haftar's "escalation" and said he had ordered loyalist forces to prepare to "face all threats".

His interior ministry announced a "state of maximum alert" and powerful armed groups from Libya's western city of Misrata said they were ready to halt Haftar's advance.

A convoy of vehicles from Haftar's forces on Thursday pushed towards the city of Gharyan, some 100 kilometres (60 miles) from Tripoli, witnesses and military sources said.

Commander Abdessalem Al-Hassi told AFP Thursday that his forces had entered into the city without a fight.

But at least four sources in the city denied this, and a Gharyan official said there were "ongoing efforts to avoid a confrontation" between rival fighters who divide the city.

Haftar has repeatedly expressed his intention to march on Tripoli.

His forces in January launched an offensive from his eastern strongholds into oil-rich southern Libya, ostensibly aimed at wiping out "terrorists" and criminal groups.

The latest rise in tensions came as United Nations chief 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.

The United States and its allies issued a joint statement urging "all parties to immediately de-escalate tensions".

Agence France-Presse