The NGOs wrote in a letter to Ban Ki-moon that the mounting death toll meant their presence at the peace table was “not only meaningless, it is unnecessary.”

Twenty-four Syrian civil society groups enlisted by the United Nations to support peace talks threatened to quit Tuesday over the failure to halt fighting in the five-year war.

The non-governmental organizations wrote in a letter to UN Secretary-General Ban Ki-moon that the mounting death toll meant their presence at the peace table was “not only meaningless, it is unnecessary.”

Among the 24 signatories were the Syrian Civil Defense, known as the White Helmets, the Syrian Network for Human Rights, the Syrian Women’s Network and the UOSSM group supporting hospitals that have come under repeated attack in the country.

“If a serious mechanism to protect our civilians and enforce the cessation of hostilities is not developed and implemented, we fear it will be impossible for our organization to continue our participation in the Geneva talks,” the groups wrote in the letter to Ban.

While the groups are not hugely influential in the peace talks, the threat to walk out underscored growing frustration with unraveling diplomatic efforts.

“After five years of conflict, our groups want a just peace, not just a peace process,” they wrote.

UN envoy Staffan de Mistura earlier this year invited civil society representatives to help support the peace process, which has been deadlocked since late April when the last round ended.

The UN-backed talks are aimed at reaching a political settlement to Syria’s five-year war, which has left more than 280,000 people dead and driven millions from their homes.

De Mistura is due to report to the Security Council on Wednesday on the state of the peace process amid much pessimism over the prospects for progress.

The envoy has yet to set a new date to resume the talks, insisting that the ceasefire reached in February must be restored and aid deliveries allowed to reach civilians in besieged areas.

The 24 groups called for breaking the sieges with air drops of aid, setting up a special tribunal to try war crimes suspects and releasing detainees.