Several European countries, including Sweden, Germany, France and Finland, are investigating or prosecuting alleged perpetrators of grave crimes in Syria in the first attempts to seek justice for victims of the conflict which is now in its sixth year.

The efforts under way in Europe follow a double-veto by Russia and China of a U.N. Security Council resolution backed by more than 60 countries in May 2014 that would have referred the Syrian conflict to the International Criminal Court.

At a U.N. panel discussion Tuesday entitled "First Cracks in the Syrian Impunity Wall," supporters and several opponents of the actions in Europe sparred over the search for justice in Syria.

Liechtenstein's U.N. Ambassador Christian Wenaweser said the European efforts should be expanded and accountability must be part of Syrian peace talks.