Iraq has blamed Iran following a breach of the border by thousands of Iranian pilgrims who reportedly broke down fences and injured guards.
The Iraqi Interior Ministry said the pilgrims who were traveling on foot to the city of Karbala to take part in Arbaeen religious rituals, overwhelmed security guards on November 29.
Arbaeen marks the end of a 40-day mourning period for the anniversary of the death of Imam Hussein, the Prophet Muhammad's grandson and the first Imam of Shi'a Islam who is buried in Iraq.
"We hold the Iranian side responsible," the ministry said in a statement issued on November 30.
It added that the breach of the border was meant "to put pressure on the crossing officials to open the border illegally."
The ministry said tens of thousands of people attempting to cross had not obtained visas, causing a stampede.
Millions of people participate in Arbaeen commemorations each year causing a security headache for Iraqi authorities.