TRIPOLI, May 9, 2026 (BSS/AFP) - Authorities in western Libya's city of Zawiya, which houses a major oil terminal and a large refinery, said on Friday they had launched a "large-scale operation" against criminal groups, as clashes and explosions were heard.

Security forces and military units carried out raids and arrests from dawn across the city west of the capital, Tripoli, by just some 45 kilometres (28 miles), an official statement said.

The operation went after "criminal hideouts and wanted individuals" who were "involved in serious acts", the authorities said, citing "murder and attempted murder, kidnapping and extortion, drug, arms and human trafficking, and illegal migration".

While authorities have yet to confirm any casualties, the UN Support Mission in Libya (UNSMIL) later in a statement condemned the clashes "amid disturbing reports of civilian casualties".

"The use of heavy weapons and indiscriminate fire in densely populated neighbourhoods is unacceptable," the mission said.

"Civilian infrastructure must not be turned into battlefields," the mission added. "All parties must immediately halt such practices and immediately cease hostilities as a matter of urgency."

Videos circulating on social media, which AFP could not independently verify, appeared to show armed clashes in residential neighbourhoods and near the refinery complex -- one of Libya's most important -- on the western outskirts of the city.

A Zawiya resident reached by AFP by phone said "the first clashes began in the early hours of Friday", adding that they heard "explosions across the city".

Local emergency services urged residents to remain indoors while midday Friday prayers -- when large numbers of worshippers go to mosques -- were set to take place.

The city of some 250,000 people has experienced repeated fights between armed groups.

In addition to housing important oil infrastructure, Zawiya has been notorious for smuggling networks involved in fuel and other smuggling across the nearby Tunisian border.

It is also a key departure point for irregular migrants seeking to reach Europe by crossing the Mediterranean.

Libya is still plagued by division and instability after years of unrest following the NATO-backed uprising that toppled longtime leader Muammar Gaddafi in 2011.

It remains divided between the UN-recognised government in the west and its eastern rival, backed by military commander Khalifa Haftar.