Iranian Foreign Minister Mohammad Javad Zarif on Sunday began a two-day visit to Iraq, which is fighting a Sunni Muslim insurgency led by Islamic State jihadists, state news agency IRNA reported.

It said he was to meet his Iraqi counterpart Hoshyar Zebari as well as the prime minister-designate, Haidar al-Abadi, with the issue of the Iran-Iraq border demarcation also on the agenda.

Iran, which like Iraq is predominantly Shiite, was a longtime backer of the outgoing premier, Nuri al-Maliki, before dropping its support of the divisive leader in favour of Abadi.

Tehran has called for Iraqi parties to unite in the face of the Islamic State which has seized large swathes of the country and says it is providing advice to Iraqi Kurds fighting the jihadists.

France, meanwhile, has pressed "all countries in the region" including Iran to join Western nations in the fight against the IS, which is also rampaging through Syria.