Iraqi Prime Minister Haider al-abadi, who is in Tehran on an official visit, has held talks with top Iranian leaders including President Hassan Rohani on the growing threat posed by Isis.
This is Abadi's first foreign trip since assuming office, as the Sunni insurgent group makes rapid advances in Iraq and the Syrian border region.
Abadi, who is leading a high-level delegation, was welcomed by Vice President Eshaq Jahangiri on his arrival.
Apart from Rohani, he also held talks with Iranian Foreign Minister Jawad Zarif.
Isis militants have seized vast areas spanning Syria and Iraq including towns which are only a few miles from the border with Iran.
Tehran, which has been strongly condemning the Isis advances, remains on high alert for any incursion by the Islamists.
Abadi's visit is to "unite the efforts of the region and the world to help Iraq in its war against the terrorist group", said a statement issued by the Iraqi prime minister's office.
Discussions pertaining to other issues such as energy and infrastructure are also expected to take place but the security situation in the wake of the Isis threat is the main item on the agenda.