Idris appeared in a Skype interview with Fox News’s Martha MacCallum from a remote location in Syria.
MacCallum told him Putin has claimed the Aug. 21 chemical weapons attack in Syria was carried out by the rebels, and not by President Bashar Assad, to provoke a response from the international community.
“I am very sorry to tell you that President Putin is lying, and he was lying from the beginning of the revolution in Syria. He knows exactly that the regime is killing our citizens,” Idris said.
The Free Syrian Army is an offshoot of Syria’s military, and among a slew of rebel groups fighting to topple Assad.
While the Obama administration has stated it has evidence more than 1,400 people were killed in the Syria attack, Idris said the number is closer to 1,800.
Putin and Obama have been in Saint Petersburg, Russia, for the Group of 20 Summit. They met for 20 minutes Friday to discuss the situation in Syria.
Russia has been supplying arms and equipment to the Assad regime, and Putin has warned the U.S. not to strike the country.
Idris said Obama needs to take action.
“We are very thankful for the decision of the president to help the Syrian revolution and the Syrian people.”