The videos, posted by the Senate Intelligence Committee on its website, show graphic images of adults and children convulsing and foaming despite no blood and obvious wounds on their bodies, signs of suffering from a chemical attack, Xinhua reported.
The videos were first played for the members of the committee Thursday at the request of its chairwoman Dianne Feinstein.
The panel said the videos were compiled by the US Open Source Center from footage taken Aug 21 in the suburbs of Damascus.
"All of the videos were posted on YouTube by pro-Syrian opposition users," the committee said in a statement.
"With one exception, all 13 videos were posted by a pro-opposition internet news channel that consistently posts user-created videos concerning the Syrian conflict."
Major US television news networks, including CNN, broadcast the videos Saturday though they admitted that they could not independently verify the authenticity of these videos.
videos were posted on YouTube by pro-Syrian opposition users
The Obama administration claims that the Syrian government perpetrated the sarin gas attack Aug 21, which the US claims killed 1,429 people, including 426 children. The videos were released to the public at a time when President Barack Obama and his Democrat allies in Congress are gearing up the campaign to swing the public opinion, which is largely against US involvement in the Syrian conflict.
Obama will conduct a series of interviews with six major US TV networks, which will air them Monday night, ahead of his scheduled televised speech from the White House Tuesday to appeal to the public for support to his plan to launch a limited military strike against Syria.