A new round of Syria peace talks opened Tuesday in Geneva as the Damascus regime fiercely denied it used a prison crematorium to hide evidence of thousands of murdered detainees.
Five previous rounds of U.N.-backed negotiations have failed to yield a solution to the six-year conflict.
U.N. envoy Staffan de Mistura met with Syrian government negotiator Bashar al-Jaafari earlier Tuesday, followed by the opposition High Negotiations Committee (HNC).
Jaafari also met with deputy Russian foreign minister Gennady Gatilov, Syria's state news agency SANA reported, before returning to the U.N. in the evening for further talks. The HNC was also due back later on.
But hopes for a breakthrough remain dim, with tensions raised further by U.S. claims of new regime atrocities at the notorious Saydnaya prison near Damascus.
The U.S. State Department on Monday accused Bashar al-Assad's government of using a crematorium to cover up the deaths of thousands of prisoners at Saydnaya -- a claim Damascus swiftly denied.