The Washington government Tuesday rejected a claim made by the Russian envoy at the United Nations that Syrian rebels used chemical weapons in their fight against the military government.

"We have yet to see any evidence that backs up the assertion that anybody besides the Syrian government has had the ability to use chemical weapons or has used chemical weapons," said White House spokesman Jay Carney at a regular press briefing.

"I think it's an interesting point that this assertion has been made to or presented to the United Nations because there is the sticking point," said Carney.

The Russian Ambassador Vitaly Churkin earlier handed over evidence to the United States, which he stated was gathered by Russian experts from the place of the attack in Syria, according to  Aljazeera.

The U.S. last month declared that the Syrian government under the regime of President Assad had used chemical weapons including the nerve agent sarin, against its rebels who were struggling to end the regime.

"Our intelligence community has high confidence in that assessment given multiple, independent streams of information," said Ben Rhodes, U.S. President Barack Obama's deputy national security adviser.

"The intelligence community estimates that 100 to 150 people have died from detected chemical weapons attacks in Syria to date; however, casualty data is likely incomplete," said Rhodes.

Citing the use of chemical weapons, the Washington government said the Assad government had crossed a "redline" and President Obama even authorized an offer of direct military aid to the Syrian rebels.

"We have consistently said the use of chemical weapons violates international norms and crosses red lines that have existed in the international community for decades," said Rhodes.

Despite Russian President Putin's objection to President Obama's nod to arm Syrian rebels, the leaders of the world's richest nations at the end of the G8 summit in Northern Ireland last month managed to issue a joint communiqué vowing full support for a political solution to the ongoing crisis in Syria.

 "We remain committed to achieving a political solution to the crisis based on a vision for a united, inclusive and democratic Syria," said the G8 statement.

Around 100,190 people have died in the Syrian civil war over the last 27 months, 36,661 of them innocent civilians, according to the Britain-based Syrian Observatory for Human Rights, which has been tracking the death toll through a network of social activists in the war-torn country.