CAIRO (AP) — Eastern Libyan forces laying siege on the country's capital, Tripoli, accused their rivals on Tuesday of staging an attack in which a Turkish drone hit a food truck convoy in the country’s west, killing at least five civilians.

The militia groups loosely allied with a U.N.-supported but weak government in Tripoli denied attacking civilians, saying instead that they targeted trucks carrying equipment and ammunition for eastern forces trying to take Tripoli.

The fighting over Tripoli erupted last April, when east-based forces under commander Khalifa Hifter launched an offensive to capture the city. In recent weeks, violence has escalated with both sides accusing each other of shelling civilian neighborhoods. The U.N. has said the violence and the worsening humanitarian crisis in Libya could amount to war crimes.

Ahmed al-Mosmari, a spokesman for Hifter forces, said the drone strike took place late Monday near the district Mizda, 184 kilometers (114 miles) south of Tripoli.

Hifter’s forces control most of eastern and southern Libya while the besieged Tripoli administration rules just a corner of the country’s west. Both sides are supported by a network of fractious militias and foreign powers.

On Monday, Hifter in an attempted show of strength, declared a 2015 U.N.-brokered political deal to unite the oil-rich country “a thing of the past.”

The Tripoli-based government said it wasn't surprised by Hifter’s announcement, and urged Libyans to join “a comprehensive dialogue and continue in the democratic path to reach a comprehensive and permanent solution based on ballot boxes.”

While the 2015 agreement has so far failed to bring unity or stability to the divided country, Hifter’s announcement threatens to further complicate U.N. efforts to broker a political settlement to the civil war.

In Brussels, European Commission spokesman Peter Stano on Tuesday criticized Hifter's announcement from the previous day, saying that “any attempt to push forward unilateral solutions, even more so by force, will never provide a sustainable solution for the country, and such attempts cannot be accepted.”

Stano said the December 2015 agreement “remains the viable framework for a political solution in Libya, until amendments are a found, or replacements are found” agreed by all parties and called on all international actors in Libya to “increase their pressure” on the warring parties to help end the fighting and bring about a political settlement.

Libya has been in turmoil since 2011, when a civil war toppled long-time dictator Moammar Gadhafi, who was later killed. The chaos has worsened in the recent round of fighting as foreign backers increasingly intervene, despite their pledges to the contrary at a high-profile peace summit in Berlin earlier this year.

Turkey has sent armored drones, air defenses and more recently, Syrian militants with links to extremist groups to prop up the embattled Tripoli government. Meanwhile, Russia has deployed hundreds of mercenaries to boost Hifter’s assault. The United Arab Emirates and Egypt also back Hifter.

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Associated Press writer Lorne Cook in Brussels contributed to this report.