At least 141 people, mostly soldiers loyal to Libya's Field Marshal Khalifa Haftar, have been killed in an attack on a southern airbase, a spokesman for his forces said on Friday.

Reports suggest the Third Force militia, which is loyal to the UN-backed Government of National Accord in Tripoli on Thursday attacked the base used by Haftar's self-proclaimed Libyan National Army (LNA).

LNA spokesman Ahmad al-Mesmari on Friday said the victims included civilians who worked at the Brak al-Shati airbase or were in the nearby area. He also reported that summary executions took place.

"The soldiers were returning from a military parade. They weren't armed. Most of them were executed," he said.

The GNA said in a statement late Friday a commission of inquiry had been set up to investigate the attack.

It said it had decided to suspend its defence minister, al-Mahdi al-Barghati, and the head of the Third Force from their duties until those responsible were identified.

The soldiers were returning from a military parade. They weren't armed. Most of them were executed - Ahmad al-Mesmari, LNA spokesman

Both the GNA and defence ministry earlier condemned the assault and said they had not ordered any such action.

Upon hearing news of the attack, the UN ambassador to Libya, Martin Kobler, expressed "outrage," saying that those killed were also civilians.

Britain's ambassador to Libya, Peter Millett, also denounced the assault.

"Disgusted by attack on Brak al-Shati & reports of mass executions. Perpetrators must be brought to justice," he wrote on Twitter.

The incident at the base in Wadi al-Shati district comes a month after an attack by the LNA on the Tamenhant airbase controlled by the Third Force near the south's main city of Sebha.

That attack was called off after a reconciliation meeting between Haftar and unity government head Fayez al-Sarraj in Abu Dhabi on 2 May.

Haftar offered chief post on accepting Libya unity government Read More »

Aguila Saleh, speaker of the eastern-based parliament, which is supported by the LNA, accused the Misrata-based Third Force of a "serious breach of the truce agreement reached in Abu Dhabi".

Saleh said there were a "number of martyrs" in LNA ranks, without giving a figure.

The speaker said he had given orders for the armed forces "to take the measures necessary to respond to the assault and defend the south and cleanse it of all outlaw militias".

Egypt on Friday condemned the offensive, with the foreign ministry calling it a "brutal terrorist attack".

The attack happened one day after Egypt's army chief of staff, Mahmoud Hegazi, visited Haftar.

Libya has been wracked by chaos since the 2011 revolt that toppled and killed longtime leader Muammar Gaddafi, with rival militias and authorities vying for control of the oil-rich country.