Libya's Government of National Accord said Sunday at least four civilians, including a child, were killed as rockets rained down on the capital Tripoli and damaged its only working airport.
The UN-recognised GNA blamed Saturday's attacks on eastern strongman Khalifa Haftar, who has been waging a campaign to take control of the capital since April last year.
GNA supporter Turkey, for its part, warned that it would target Haftar's forces if attacks continued on Ankara's missions and "interests", citing the airport.
Haftar's forces "fired more than a hundred rockets and missiles at residential areas in the centre of the capital", the GNA said in a statement on Facebook.
At least four civilians, including a five-year-old girl, were killed and 16 others wounded in the working-class districts of Abu Slim and Ben Gashir, south of the city, the GNA's health ministry spokesman Amin al-Hashemi said.
Dozens of rockets also targeted Mitiga airport, hitting a civilian aircraft lined up to repatriate Libyans stuck abroad due to the coronavirus pandemic, the GNA statement added.
Turkey warned that Haftar's forces would become "legitimate targets" if such attacks continued.
Overnight Thursday to Friday, rockets fell on Tripoli's Zawiyat al-Dahmani neighbourhood, which is home to the GNA foreign ministry and the Italian and Turkish embassies.
At least two policemen and one civilian were killed, Hashemi said at the time.
"We stress that if our missions and interests are targeted in Libya, Haftar's forces will be considered legitimate targets," the Turkish foreign ministry said.
"The attacks on diplomatic missions including our Tripoli embassy, Mitiga airport, civilian planes preparing to take off and other civilian infrastructure, and those which kill civilians or injure them, constitute a war crime," it added.
Mitiga airport was badly damaged Saturday and came under renewed rocket fire on Sunday morning.
An airport source said the passenger halls and two civilian planes sustained serious damage.
Images of an aircraft with its fuselage ripped open and of a badly damaged runway and airport buildings were posted on social media.
Libya's National Oil Corporation (NOC) said Saturday that rockets and missiles hit a fuel depot at the airport, destroying four tanks and damaging the facility's other six.
'Weakness and desperation'
The United Nations Support Mission in Libya (UNSMIL) called the bombardment "an all too familiar but frightening spectacle".
"These horrifying attacks occur on a regular basis in close proximity to civilian neighbourhoods," UNSMIL said on Twitter.
It called the shelling "one in a series of indiscriminate attacks, most of which are attributable to pro-LNA (Haftar) forces, killing more than 15 and injuring 50 civilians since 1 May".
Since Wednesday, 17 civilians and two police officers have been killed and more than 66 other civilians wounded in rocket fire targeting several areas of the capital, according to the GNA.
UNSMIL slammed the attacks hitting civilians and civilian infrastructure and called for "those responsible for crimes under international law to be brought to justice".
But the GNA said international condemnation was not enough.
"We no longer pay any attention to the timid condemnations of the international community, incapable as it is of naming" Haftar, holding him to account or stopping those supporting him, the GNA said.
"The senseless acts... of the past days... are proof of his weakness and desperation after the successive defeats of his militias and mercenaries," it added.
Haftar's forces have suffered several setbacks in recent weeks, with GNA fighters ousting them from two key coastal cities west of Tripoli in April.
Backed by Turkey, GNA troops now surround Haftar's main rear base at Tarhuna, southeast of the capital.
Turkey's foreign ministry said the international community had a "collective responsibility" to stop "putschist Haftar".
Foreign military involvement in Libya has exacerbated the conflict, with the United Arab Emirates and Russia backing Haftar.
World leaders at a Berlin meeting in January committed to ending foreign meddling and to upholding a 2011 weapons embargo, but the UN has warned that both sides have continued to receive arms and fighters.