GENEVA - UN Syria envoy Staffan de Mistura said Syria talks in the Kazakh capital Astana on Friday had agreed on a 'working group' for the release of detainees, which he said was a commendable first step towards an arrangement between the warring sides. He also said that Russia's plan to convene a Syrian 'congress of national dialog' in Sochi next month should be assessed by its ability to contribute to and support the UN-led Geneva talks on ending the war in Syria.