Nine more bodies were discovered and exhumed at a site thought to contain more remains in the town of Tarhuna, GNA forces say with authorities suspecting the presence of other potential graves as well.
Nine bodies have been found in another mass grave in the Libyan town of Tarhuna.
Southeast of Tripoli, Tarhuna once served as the main staging point for warlord Khalifa Haftar's abortive offensive aimed at seizing the capital from the UN-recognised Government of National Accord (GNA).
"Nine bodies were discovered and exhumed on Sunday ... at a site suspected of containing mass graves, in the town of Tarhuna," said a statement posted on Facebook by GNA forces on Monday.
Government forces earlier this month said they had discovered eight other suspected mass graves, most of them in and around Tarhuna, with the United Nations voicing "horror" at the reports.
Monday's statement said authorities were still searching for other potential mass graves "left by the Al Kani criminal gangs, a pro-Haftar militia."
Evidence of war crimes
Government forces took back Tarhuna, Haftar's last western stronghold, on June 5.
The 14 months of fighting for the capital left hundreds dead and forced some 200,000 people to flee their homes.
Turkey supports the GNA while the United Arab Emirates, Russia and Egypt back the LNA, Haftar's Libyan National Army.
On June 22 the UN's top rights body ordered a fact-finding mission to Libya to document violations committed since 2016, while an International Criminal Court prosecutor said mass graves discovered there may constitute evidence of war crimes.
Oil-rich Libya has been torn by conflict since the 2011 toppling and killing of former leader Muammar Gaddafi in a NATO-backed uprising.
Libya's NOC confirms talks on resuming oil output
Libya's National Oil Corporation (NOC) is hopeful that oil production will resume after international talks to end a blockade by militias based in the east of the North African country, a spokesman has said.
Though Libya has been divided since 2015 between the rival sides, international agreements stipulate that only the NOC is allowed to produce and export oil and the blockade has cost Libya billions of dollars in revenue.
There have been negotiations in recent weeks between NOC, the GNA and regional countries, overseen by the United Nations and United States, an NOC spokesman said in a statement.
"We are hopeful that those regional countries will lift the blockade and allow us to resume our work," the spokesman said.
The NOC reported earlier on Friday that Russian and other foreign mercenaries entered Libya’s largest oil field, describing the development as an attempt to thwart the resumption of halted oil production in the war-torn country.
The Russian mercenaries first met late on Thursday with the guards of Libya’s vast southwestern Sharara oilfield, controlled by Hafter militias, according to a statement from the NOC.
The blockade was imposed as increasing Turkish support for the GNA called into question the LNA's ability to sustain its attack on Tripoli.
The GNA says the Haftar's militias are behind the blockade, which was announced in January by local groups including tribes. The LNA says the tribes imposed the blockade to seek a greater share of revenue.
Control over oil output and revenue is a major prize for both sides, as well as for the foreign backers who have played an ever bigger role in the war in recent months.
The division of revenue, paid into the Tripoli-based Central Bank of Libya and used to fund state institutions around the country and across the front lines, remains a source of contention.
"We need to resume work immediately to save our infrastructure and the Libyan economy," the NOC statement said.
"NOC is determined that the agreement will guarantee transparency and that oil revenues will achieve social justice for all Libyans," it said.
Turkish company prepping offer to supply power
Turkish power-ship operator Karadeniz Holding is preparing a bid to supply up to 1,000 megawatts of electricity to conflict-hit Libya and will submit it soon, the company said on Monday.
Libya has been hit by power supply problems due to the civil war there.
A senior Turkish official told Reuters two weeks ago Turkey is ready to start rebuilding Libya after President Recep Tayyip Erdogan's senior deputies visited Tripoli to discuss cooperation on energy, construction and banking.
Karadeniz –– whose Karpowership supplies power to more than 10 countries in Africa, the Middle East and the Caribbean –– would be a company capable of making up the energy deficit in Libya, the Turkish official had said.