The UN's former chief prosecutor Carla del Ponte said Monday that the International Criminal Court should be called in to probe war crimes in Syria and bring the perpetrators to justice.
Issuing a report by a UN commission of inquiry that found war crimes by both government forces and rebels were spiralling amid an increasingly radicalised and sectarian conflict, del Ponte said it was time to act.
"We suggest the International Criminal Court. We can't decide, but we are pressuring the international community to act, because it's time to act," said del Ponte.
"It's time to react. After two years, it's incredible that the Security Council hasn't made a decision," she told reporters in Geneva as the commission prepared to submit a list of perpetrators who should face justice.
"Justice must be imminent, urgent. The number of victims is increasing day to day. Justice must be done."
Officials at the Netherlands-based ICC declined to comment on del Ponte's call, but spokesman Fadi El Abdallah underlined that Syria has not ratified its founding statute.
"The ICC does not have jurisdiction over alleged crimes related to non-party States unless the UN Security Council refers the situation to the ICC," he told AFP.
The Security Council is split between Western members and Russia, a staunch Syrian ally, plus China.
China has backed Russia in vetoing Security Council resolutions that would have put greater pressure on President Bashar al-Assad's regime. Beijing has also repeatedly urged dialogue to end the violence.
Even if the Security Council called in the ICC, it would be up to the court whether to open a case.
"Any decision to open an investigation remains a legal decision made by the ICC as an independent judicial institution and after a legal analysis of the situation and the alleged crimes," said El Abdallah.
Del Ponte said that the inquiry team's work had paved the way.
"It's not enough, let's say, to prepare an indictment, but of course there is strong evidence," she said. "It should be further investigated."
Del Ponte gained renown for her tough stance as the UN's war crimes prosecutor for the former Yugoslavia.
"I'm not the prosecutor dealing with this case. Unfortunately," she said Monday.
Speaking by telephone from his homeland Brazil, commission head Paulo Pinheiro refused to be drawn on the individuals and Syrian military and rebel units accused of war crimes.
The commission -- set up in 2011 at the behest of the UN Human Rights Council -- is to submit a confidential list of names to the UN's human rights office next month.
-- Conflict increasingly 'radicalised and militarised' --
Syria has been embroiled in conflict since Assad's regime launched a brutal crackdown on protests that erupted in March 2011. The United Nations says about 70,000 people have been killed.
Unable to gain access to Syria since Damascus has ignored its request for entry, the commission has interviewed over 1,500 refugees and exiles.
"The conflict has become increasingly sectarian, with the conduct of the parties becoming significantly more radicalised and militarised," said Monday's report.
Pinheiro warned that foreign fighters, honed in conflict zones such as Libya or Afghanistan, were driving that trend in the rebel camp.
Most of the rebels are Sunni Muslims, while the ruling clan and many of its most fervent supporters are from the minority Alawite sect, an offshoot of Shiite Islam.
"Government forces and affiliated militia committed the crimes against humanity of murder, torture, rape, enforced disappearance and other inhumane acts," the report said.
The commission also lambasted the rebels, saying that "anti-government armed groups have committed war crimes, including murder, torture, hostage-taking and attacking protected objects".
"They continue to endanger the civilian population by positioning military objectives inside civilian areas," the report said.
But it underlined that the regime was still the major perpetrator.
"The violations and abuses committed by anti-government armed groups did not, however, reach the intensity and scale of those committed by government forces and affiliated militia."