Carla Del Ponte, a member of the U.N. Independent International Commission of Inquiry on Syria, said testimonies from the victims strongly suggest it was the rebels that used Sarin nerve gas in the eastern Gouta.

Carla Del Ponte, a member of the U.N. Independent International Commission of Inquiry on Syria, said testimonies from the victims strongly suggest it was the rebels, not the Syrian government, that used Sarin nerve gas in the eastern Gouta.

The UN official told Swiss TV there were "strong, concrete suspicions," that the rebels had used the nerve agent.

She added that her panel had not yet seen any evidence of Syrian government forces using chemical weapons, according to the BBC, but she stressed more investigation was needed.

Damascus has repeatedly denied growing Western accusations that its forces used such weapons, which President Obama has described as crossing a red line.

"Our investigators have been in neighboring villages interviewing victims, doctors and field hospitals. According to their report of last week, which I have seen, there are concrete suspicions of the use of sarin gas, from the way the victims were treated," Ms. Del Ponte, a former Swiss prosecutor and attorney general, told Swiss TV.

The UN Independent International Commission of Inquiry on Syria was established in August 2011 to examine alleged violations of human rights in the Syrian crisis which started in March that year.