Forces of the Libyan National Army (LNA) said they launched air strikes early Tuesday against an airbase in third city Misrata held by UN-recognised government loyalists.
"Our air force carried out several raids against the Misrata airbase, targeting anti-air defences as well as a Turkish aircraft transporting ammunition, drones and missiles," LNA lead by Khalifa Haftar said in a statement on its Facebook page.
Pro-LNA television channel Libya Al-Hadath said a Turkish Ilyushin aircraft "was destroyed as it landed at the Misrata base".
It aired footage, which could not be independently verified, of the alleged strikes.
Forces loyal to the UN-recognised Government of National Accord (GNA) did not immediately confirm or deny the reported attack.
LNA forces launched an offensive in April to wrest Tripoli from the GNA.
Many of the government's best equipped and most seasoned fighters come from Misrata, which is east of the Libyan capital.
Tuesday's air strikes came a day after the GNA and a local official reported the death of at least 42 people in a raid targeting a town hall meeting in southern Libya.
Dozens more were wounded in Sunday night's attack which the GNA said was carried out by LNA forces.
UN envoy Ghassan Salame has repeatedly denounced an escalation of violence between the two camps and called for negotiations.
Last week he proposed a ceasefire for the Muslim holiday of Eid al-Adha due to start on August 10.
The World Health Organization says the battle for Tripoli has left nearly 1,100 people dead and wounded more than 5,750, while forcing more than 100,000 civilians to flee their homes.
*This article was edited by Ahram Online