Iran has stepped up surveillance along its long border with Iraq in precaution against a spread of violence from armed mercenaries of ISIL who have seized a swathe of its neighbor.

Iran has stepped up surveillance along its long border with Iraq in precaution against a spread of violence from armed mercenaries of the so-called 'Islamic State of Iraq and the Levant' (ISIL) who have seized a swathe of its neighbor, a senior official said on Monday.

"Due to the unique situation in Iraq and its proximity to our western regions, we have taken duly precautions to shore up control, watch and fortifications along the border," Interior Minister Abdolreza Rahmani-Fazli told reporters.

"But presently we have no worries," the minister was quoted as saying by the official news agency IRNA.