(CNN) Veteran war crimes prosecutor Carla del Ponte is quitting the UN's Independent International Commission of Inquiry on Syria, the panel confirmed on Sunday .

Del Ponte was one of three members on the UN-appointed panel tasked with probing human rights violations in Syria, including chemical weapons attacks, torture of prisoners, and the targeting of hospitals.

"I am quitting this commission, which is not backed by any political will," she told a panel discussion at the Locarno Film Festival, Reuters reported

"I have no power as long as the Security Council does nothing," she added. "We are powerless, there is no justice for Syria."

Del Ponte has served on the commission since September 2012 -- one year after the Syrian conflict started. Since it began, the Syrian civil war has left some 400,000 people dead and millions displaced

The UN Commission of Inquiry said in a statement that its work would continue after del Ponte's departure.

"It is our obligation to persist in its work on behalf of the countless number of Syrian victims of the worst human rights violations and international crimes known to humanity," the commission said, thanking del Ponte for her contributions. "Such efforts are needed now more than ever."

Del Ponte informed her colleagues, Brazil's Paulo Pinheiro and Karen Koning AbuZayd from the United States, in mid-June of her decision to leave, according to the statement.

The commission, which was appointed by the Geneva-based United Nations Human Rights Council, has produced a number of reports chronicling evidence of war crimes and crimes against humanity. In 2016, the panel found that ISIS had committed genocide against the Yazidi religious minority. In the same year, it documented how government forces unlawfully detained and tortured people in Syrian prisons

In order to prosecute such crimes, the Security Council must refer the conflict to the International Criminal Court, which is unlikely given Russia's power to veto such a move. Russia has supported Syria since the beginning of the conflict in 2011, providing military assistance to President Bashar al-Assad's government.

Del Ponte, a former Swiss attorney general who made her name prosecuting war crimes in Rwanda and the former Yugoslavia, said the crimes she's seen in Syria are unparalleled -- hinting at her exasperation over a lack of accountability.

"What we have seen here in Syria, I never saw that in Rwanda, or in former Yugoslavia, in the Balkans. It is really a big tragedy," she added. "Unfortunately we have no tribunal."