French Prime Minister Jean-Marc Ayrault presented a report to parliament where he claimed the Aug. 21 assault included a “massive use of chemical agents.”

Ayrault also claimed in the report that 281 deaths could have been prevented, BBC News reports. France has been backing the United States as both want to conduct a military strike upon Syria for allegedly using chemical weapons.

The U.K. parliament voted down any chance of involvement in a military strike last week, and wants to wait and see what U.N. investigators find before making any other decisions.

Talking to French newspaper Le Figaro, Bashar al-Assad, the Syrian president, resumed denying his government carried out any chemical attack saying it is “illogical.” He also said there would be “repercussions” for any military strike.

“Everyone will lose control of the situation when the powder keg explodes. Chaos and extremism will spread.”

The Telegraph notes that the report also says French military doctors have authenticated 47 video clips taken during the time of the attack. They also believe that though 281 can be confirmed through the amateur video, it was likely to be closer to 1,500 deaths in reality.

French President Francois Hollande remains the only western leader who has not put the possibility of a military strike to a vote.