The US has pointedly rejected Iran’s presence in an international conference on action in the Iraqi crisis against the Islamic State, with Secretary of State John Kerry labelling Tehran “a state sponsor of terror” and a backer of the brutal Assad regime in Syria.

Kerry was meeting Turkish leaders to discuss the coalition to support an Iraqi and Kurdish counter-offensive against the jihadists after their advance through northern and western Iraq.

The conference is scheduled for Monday in Paris.

The Secretary of State said, “Under the circumstances, at this moment in time, it would not be right for any number of reasons. It would not be appropriate given the many other issues that are on the table in Syria and elsewhere.”

Iranian media have presented the enthusiasm of the international community for Tehran’s involvement. On Friday, Press TV featured an interview in which Iraqi President Fuad Masum reportedly said Iran would be invited along with Arab States and Turkey.

President Rouhani used an address to the Shanghai Cooperation Organization summit in Tajikistan on Friday to call for Iran’s inclusion. He declared that airstrikes alone would not confront the Islamic State: “Fighting terrorism needs organized planning, bilateral and multilateral cooperation and elimination of economic and cultural poverty.”

Meanwhile, Iran’s officials and outlets have launched scathing attacks on the US as the supposed founder and supporter of the Islamic State. The Iranian military and clerics repeated the allegation on Friday, with Tehran Friday Prayer leader Ayatollah Mohavedi Kermani insisting, “Terrorist groups such as Al Qa’eda and the Islamic States were created by the West and the United States.”

The Iranian campaign appears to be based on fears of increasing US intervention in Iraq. The Americans have put special forces on the ground, as President Obama authorized the deployment of more than 1,000 personnel since June, while US warplanes have hit Islamic State targets since August 8.

At the same time, the US and Iran have been de facto allies in certain operations. Last month, American airstrikes and Iranian military advisors on the ground supported an Iraqi-Kurdish offensive breaking the two-month siege of the town of Amerli in northern Iraq.