Libyan unity government forces said Tuesday they had downed an Emirati-supplied drone used by eastern strongman Khalifa Haftar's forces in the country's west, as three schoolchildren were reported killed in a Tripoli rocket attack.

The Tripoli-based Government of National Accord (GNA) said its "anti-aircraft defences" downed the drone east of Misrata, Libya's third largest city. The health ministry later said three children, aged between nine and 12, were killed in a rocket blast on a road near a school in the Hadhba al-Badri district of southern Tripoli.

GNA loyalists accused Haftar's forces, engaged in a months-long offensive to seize the capital, of carrying out that attack. The unity government's forces on Tuesday posted images on Facebook showing what appeared to be the charred remains of a Chinese-made Wing Loong drone.

The downing of the drone came days after the United Nations slammed "continued blatant violations" of a 2011 arms embargo -- despite world leaders committing in mid-January to upholding the blockade. Experts say Haftar has procured a number of the aircraft from the United Arab Emirates, his main backer.

Haftar, who controls much of eastern and southern Libya, launched an offensive in April to seize the capital Tripoli, on the northwestern coast, from the GNA. His advance stalled on the edges of the capital, but in early January he captured the strategic coastal city of Sirte.

On Sunday, his forces clashed with those of the GNA in the Abu Grein region, on the road west from Sirte towards Tripoli and Misrata -- the hometown of many of the forces backing the GNA. Advanced UAE-supplied drones have given Haftar an advantage in the skies.

Turkey has supplied the GNA with Bayraktar drones, but they have proven less sophisticated and prone to being shot down by Haftar's forces. On Sunday, Germany's foreign ministry echoed UN concerns over arms flowing to Libya, citing "a series of unconfirmed but credible reports of embargo violations on both sides".

That comes despite a January 12 ceasefire announced by Haftar backer Moscow and pro-GNA Ankara. Each side has repeatedly accused the other of violations.