"We have given help with policy and advice to the Iraq government. We have acted in the same manner to Iraqi Kurdistan," Amir-Abdollahian told the Arabic service of state television.

Tehran has no military presence in Baghdad, the Shiite shrine city of Samarra to its north or the Kurdish region of Iraq, he added. "We have not sent arms either," Amir-Abdollahian said.

Iran, majority Shiite like its neighbour Iraq, was a principal supporter of divisive former Iraqi premier Nuri al-Maliki before the turmoil led it to distance itself from him.

It has welcomed the appointment of Maliki's successor, Haidar al-Abadi, and has called on all Iraqi parties to unite against the IS offensive.

IS and its Sunni allies have overrun large chunks of Iraq and neighbouring Syria, and have declared a cross-border caliphate -- a successor state to historic Muslim empires.