As videos of an alleged chemical attack in Syria were shown to the world, some experts cast doubt on their authenticity.

Stephen Johnson is an expert in weapons and chemical explosives at Cranfield Forensic Institute. He said there were inconsistency among the patients’ symptoms.

“There are, within some of the videos, examples which seem a little hyper-real, and almost as if they’ve been set up. Which is not to say that they are fake but it does cause some concern. Some of the people with foaming, the foam seems to be too white, too pure, and not consistent with the sort of internal injury you might expect to see, which you’d expect to be bloodier or yellower,” Johnson said.

Johnson said that although much of the video showed injuries consistent with trauma to the nervous system, it was too early to conclude that it was from chemical weapons.

“At this stage everyone wants a ‘yes-no’ answer to chemical attack. But it is too early to draw a conclusion just from these videos,” he added.

Syrian anti-government activists claim regime forces targeted eastern suburbs of Damascus with a toxic gas.

France and Britain have called for UN inspectors, who are already in the country, to be allowed immediate access to the site.