"The toll of the Tripoli crisis is now 607 dead, including 40 civilians, and 3,261 wounded, including 117 civilians," WHO tweeted.
The east-based army, led by Khalifa Haftar, has been leading a military campaign since early April to take over Tripoli, where the UN-backed government is based.
The army denied on Sunday any cease-fire with the Government, confirming that "significant changes" on ground will be made soon.
Libya has been struggling to undergo a transitional period amid chaos since the fall of former leader Muammar Gaddafi in 2011.
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