The claim of responsibility made no mention of the US withdrawal. Instead, it focused on the country’s Shia-dominated leadership, which Sunni insurgents have battled since it came to power as a result of the US-led invasion that toppled Saddam Hussein in 2003.

“The series of special invasions [was] launched … to support the weak Sunnis in the prisons of the apostates and to retaliate for the captives who were executed,” the statement, in the name of the Islamic State of Iraq, said.

According to the Site Intelligence Group, a US-based organisation that monitors jihadist websites, the claim of responsibility was posted late on Monday.

The group said the attacks were proof that they “know where and when to strike and the mujahideen will never stand with their hands tied while the pernicious Iranian project shows its ugly face”.