The UN's Libya envoy has warned an agreement between the strife-torn country's rival political factions is still a way off, as fighting for control of the capital raged for a second day.
Libya has been wracked by violence since the NATO-backed uprising that toppled longtime dictator Moamer Kadhafi in 2011, with rival militias and administrations battling for power.
Three days of UN-mediated talks that began on Friday are aimed at reaching an agreement to form a national unity government.
"An agreement is going to be difficult, we are still a long way off," UN special envoy Bernardino Leon told Spanish daily newspaper El Pais from Morocco.
As the talks got under way, the internationally recognised government said loyalist forces had launched an offensive to "liberate" Tripoli, seized by Islamist-backed militia last summer.
On Friday, an AFP photographer said, there was fighting between them and militias of the Fajr Libya coalition in the vicinity of Aziziya, 35 kilometres (22 miles) south of the capital.
On Saturday, there was further fighting in another sector 80 kilometres to the south.
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"We think this activity is linked to the negotiations," Leon was quoted by El Pais as saying.
"In both camps, there are the hardliners and the moderates," he said. "The moderates want to reach an agreement, while the hardliners prefer a military solution, they want to impose it on the other party by force."
"The international community can't accept such an outcome.
"What the international community didn't do well after the 2011 intervention is not to stay on the ground. It wasn't about rebuilding a state, it was about building one from scratch," he said.
Leon later called the latest fighting an "operation that we condemn in the strongest terms because it's undermining the dialogue in the decisive moment".
Leon has said the talks in Morocco would focus on security arrangements, the creation of a national unity government and confidence-building measures.
"By Sunday, we would like to have these three documents ready and if possible, published, as already agreed (as) part of what will be a final package," he has said.