The border will remain shut until “further notice”, Iran’s Tasnim news agency said.
The crossings at Shalamcheh and Jithba, near the southern Iraqi city of Basra, were closed to pilgrims on the decision of an Iranian committee set up for the pilgrimage, which begins next Friday and will last for two days.
"All borders with Iraq have been closed until further notice due to concerns about the safety and security of visitors," Tasnim quoted the head of the committee, Majid Mir Ahmadi, as saying.
The "internal situation in Iraq will be assessed in terms of congestion, and a decision will be taken to reopen the borders," he said.
The Arbaeen pilgrimage is considered the most important religious event for Shiite Muslims and draws millions from all over the world to the southern Iraqi cities of Najaf and Karbala. It marks the end of a 40-day mourning period for a grandson of the Prophet Mohammed, Imam Hussein, who was killed in battle in 680.
Foreign pilgrims were mostly barred from entering Iraq after the onset of the Covid-19 pandemic in 2020. The ban remained in place the following year despite the country beginning to ease its travel and entry restrictions.
However, this year Iranians are being allowed to enter Iraq without the need to get visas.
Iranian Interior Minister Ahmad Vahidi, during a visit to Iraq on Thursday, said officials in Baghdad and Tehran were seeking to ensure the safety of the Arbaeen pilgrims.
He said a large number of Iranian pilgrims had already travelled to Iraq and praised the Iraqi government, army and police for enabling their safe entry.
Iranians usually make up the largest number of foreign pilgrims for Arbaeen. Tens of thousands walk part of the way from Iran to Karbala.
Nearly 1.3 million pilgrims have already arrived from various countries, Iraqi officials said this week.