Russia labels US claims of chemical weapons usage in Syria as 8216;unconvincing8217;

A U.S. official said on Thursday that President Barack Obama had authorised sending U.S. weapons to Syrian rebels for the first time,after the White House said it had proof that the Syrian government had used chemical weapons against opposition forces.

U.S. officials briefed Russia on the information they had,Ushakov said at a briefing before Putin8217;s trip to Northern Ireland for a G8 summit. 8220;But I will say frankly that what was presented to us by the Americans does not look convincing.8221;

8220;It would be hard even to call them facts,8221; said Ushakov,speaking at a briefing before a summit where Putin will meet Obama and other Western leaders.

8220;If the Americans carry out more wide-scale aid to the rebels and opposition,it will not make organising the international conference easier,8221; he said.

But he said Russia was not 8220;competing8221; with the United States over Syria. Asked whether Moscow would send Assad the S-300 missile systems that Israel and the West have urged it not to deliver,he said: 8220;We are not talking about that yet.8221;

Russia and the United States are trying to bring Syria8217;s government and rebels together for talks,but have not secured a commitment from either side to participate.