US President Barack Obama has described allegations of a chemical attack in Syria as a "big event of grave concern" and said that it would be "very troublesome" if they were verified.
He told CNN's 'New Day' programme that he does no expect the Syrian regime of President Bashar al-Assad to cooperate, based on previous experience.
Asked about the so-called "red line" that he previously said a chemical attack would represent, he admitted he still had to look at the latest event in detail.
Britain has directly accused the Assad regime of gassing hundreds of Syrian civilians amid warnings only 48 hours remain to find proof.
New videos show the eyewitness accounts of four men who witnessed an alleged chemical attack on Zamalka, a suburb of Damascus.
These are the images of the remains of rockets which, according to the men stood by them, delivered poisonous gas to a suburb of Damascus.