A helicopter with 23 people on board crashed Tuesday near the Libyan capital but the cause was unclear, a security official said.
There were unconfirmed reports that several senior members of the militia coalition that controls Tripoli could have been on board.
"We don't know the number of victims or if there are survivors," the Tripoli-based official told AFP.
The North African nation has seen widespread violence since the 2011 overthrow and killing of longtime leader Moamer Kadhafi.
The helicopter came down near the town of Zawiya, around 45 kilometres (30 miles) west of the capital, according to the LANA news agency which is close to the internationally recognised government.
It said that several commanders of the Fajr Libya (Libya Dawn) militia coalition could have been travelling on the aircraft but there was no confirmation.
Libya has been rocked by deadly clashes between militiamen and forces loyal to the internationally recognised government, which has taken refuge in the country's far east.
The international community is pressing Libya's warring factions to sign a peace deal to calm turmoil that has been exploited by jihadists and people smugglers.