Libya's UN-recognised government on Sunday condemned overnight air raids against a recently recaptured airbase in the west of the country saying the attack was carried out by a "foreign air force".
Fighters loyal to the Government of National Accord (GNA) seized back the al-Watiya airbase, 140km (90 miles) southwest of the capital Tripoli, from troops aligned with renegade military commander Khalifa Haftar in May.
Haftar's self-styled Libyan National Army (LNA) alleges Turkey - a key GNA backer - subsequently made use of the base to help GNA soldiers repel an offensive it launched against Tripoli in April last year.
Al-Watiya's recapture marked the start of the sudden collapse of the LNA's 14-month assault to seize the capital and led to its hasty retreat along the coast.
"The raids last night against Al-Watiya base were carried out by a ... foreign air force in support of the war criminal [Haftar] in a miserable and desperate attempt to achieve a morale-boosting victory," GNA Deputy Defence Minister Salah al-Namrush said in a statement.
He promised a "response in the right place and at the right time", saying the attacks were "a failed attempt to distract from recent victories" by the GNA.
Al-Namrush did not specify which foreign air force was behind the air raid.
Citing military sources, pro-Haftar media earlier reported the air raids were carried out by "unknown planes" that targeted a Turkish aerial defense system installed at al-Watiya.
Turkey's state news agency Anadolu, quoting an unnamed GNA military official, said the raid against al-Watiya was carried out by "unidentified planes" and there were no casualties.
"Materials recently deployed to reinforce anti-aerial capacities were damaged," Anadolu reported.
Plunged into chaos by the 2011 NATO-backed uprising that toppled and killed its longtime leader Muammar Gaddafi, oil-rich Libya has two rival administrations in the west and east of the North African nation.
Haftar's forces are backed by Egypt, Russia, and the United Arab Emirates (UAE). His fighters withdrew from the southern outskirts of Tripoli and the entire west of the country in June after a string of battlefield defeats to the Turkish-backed GNA.
Turkish support was vital to the GNA in turning back the LNA offensive with advanced air defences and drone attacks that targeted Haftar's supply lines and troop build-ups.
A Turkish source said last month Turkey was in talks with the GNA to establish two military bases in Libya, one at al-Watiya - the most important airbase in western Libya.
Turkey's Defence Minister Hulusi Akar was in Tripoli for meetings with the GNA on Friday and Saturday.
During its advance towards Tripoli last year, the LNA was assisted by Egyptian and UAE air raids. Last month, the United States said Russia had sent at least 14 MiG29 and Su-24 warplanes to an LNA base.
The GNA and LNA are now mobilising forces at the new front lines between the cities of Misrata and Sirte.
Egypt has warned any Turkish-backed effort to take Sirte, which the LNA captured in January, could lead its army to directly intervene.