The US Senate Intelligence Committee released video footage showing victims of an alleged Syrian nerve gas attack on Saturday.

The video was shown during a classified briefing to members of the Intelligence Committee on Thursday as part of the Obama administration's attempt to drum up congressional support for a limited military strike against Syria.

The footage was filmed by Syrians and had previously been publicly made available on Youtube and other websites, but was confirmed as authentic by the Central Intelligence Agency.

The horrifying images show Syrian men, women and children struggling to breathe and convulsing. They are the apparent victims of nerve gas poisoning.

The graphic images have been held up by US Secretary of State John Kerry as proof positive the Assad regime used the chemical agent sarin in the early morning attack in a rebel-held Damascus suburb on August 21.

"Those videos make it clear to people that these are real human beings, real children, parents being affected in ways that are unacceptable to anybody, anywhere by any standards," Kerry said during a news conference in Paris.

"And the United States of America that has always stood with others to say we will not allow this - this is not our values, it's not who we are."

Nerve agents such as sarin are typically delivered via a binary shell containing two component chemicals.

Upon firing, the rupture discs separating the chemicals break.

The spinning of the shell mixes the chemicals together to form the toxic agent, which is released upon impact.

Sarin can be inhaled, ingested or absorbed through the skin. Once inside the body sarin attacks the central nervous system bringing an agonizing death to those exposed to large doses.

A team of U.N. investigators were dispatched to the suburbs of Damascus to meet and take samples from victims of the attack.

The European Union on Saturday urged the US hold off on military action until the preliminary report was submitted.

US intelligenc