Ms. Bishop described the group as one of the “gravest security threats we face today”.

She said Australia had no doubt that the Syrian regime had used toxic chemicals, including sarin and chlorine, over the past four years.

The use of chlorine in homemade bombs has been reported in several parts of Iraq and Syria.

“They seek to undermine and overthrow that order and as we have seen, are prepared to use any and all means, any and all forms of violence they can think of to advance their demented cause,” she said.

“That includes use of chemical weapons,” Ms. Bishop said.

“Daesh is likely to have amongst its tens of thousands of recruits the technical expertise necessary to further refine precursor materials and build chemical weapons,” she said.

She was speaking at the 30th anniversary of the Australia Group which is an informal alliance of countries that seeks to prevent the export of materials that can be used in the development of chemical weapons.

“Chemical weapons often receive less public attention than nuclear and biological threats,” she said.

“However, toxic chemicals were, by far, the most widely used and proliferated weapons of mass destruction in the 20th century,” she said.