A Russian official has said it is "impossible" to organise an international conference by the end of this month which eventually aims to bring together the Syrian government and opposition for negotiations.
Washington and Moscow announced joint plans earlier this week for such a summit, which would work towards ending the country's bloody civil war.
The Russian official, who was at yesterday's talks between President Vladimir Putin and Prime Minister David Cameron, said: "By the end of May is impossible".
The anonymous official said disagreements remained about who could take place in the peace process.
More top news
Their relief of Scottish banks, estate agents and other businesses this morning is obvious after the country voted to stay in the UK.
The referendum story is rapidly heading south. Scottish voters were promised more power - now English and Welsh voters ask "what about us?"
The Scottish independence referendum was threatening to turn into a huge boost for separatist movements in many countries in Europe.