U.S. President Barack Obama on Wednesday refused to specify the exact nature of new U.S. military aid to Syrian rebels, despite signals from top U.S. officials that they will be get small arms and ammunition.

U.S. President Barack Obama on Wednesday refused to specify the exact nature of new U.S. military aid to Syrian rebels, despite signals from top U.S. officials that they will be get small arms and ammunition.

"I cannot and will not comment on specifics on our programs related to the Syrian opposition," Obama said at a joint press conference with German Chancellor Angela Merkel in Berlin.

Obama has refused to publicly specify exactly how Washington will increase aid to the Syrian opposition, after his government said it would offer military support for the first time after insisting President Bashar al-Assad had used chemical weapons, even though he didn’t present any proof for his claims.

Previously Obama had warned against pouring more weapons into the conflict and had kept U.S. aid limited to humanitarian and non-lethal supplies.

The U.S. president also said in Berlin that reports in the United States that escalating American support to the militants meant the White House was now on a slippery slope to a new Middle East entanglement were mistaken.

He said reports were "over cranked" when suggesting the U.S. was heading into a new Middle Eastern war.

"What we want to do is to end a war," he said, calling again for a political transition in Syria that does not include Assad.

For her part, Merkel said Berlin agreed that "Assad has lost his legitimacy" but reiterated the stance that "Germany has very clear legal rules that we do not send weapons into civil wars", saying this was universal and "has nothing to do with the question of Syria specifically".

But she added: "This doesn't mean that we can't play a constructive role in the political process, humanitarian aid and the question about the right way" to help the moderate opposition and the people of Syria.