Hojat-ol-Islam Sohbatollah Rahmani said all of those who want to go on the spiritual journey are required to register their names on a special website named Samah.
He noted that Iraq has removed visa requirements for Arbaeen pilgrims from Iran this year but they still need to have their Samah registration card and passports with them in order to cross the border.
According to Hojat-ol-Islam Rahmani, based on an agreement signed between Tehran and Baghdad, the pilgrims can go to Iraq without a visa from September 10 to November 7.
Officials from Iran and Iraq agreed in July to process visa-free entry of millions of Iranians who travel to Iraq during the annual pilgrimage period.
Arbaeen comes 40 days after Ashura, the martyrdom anniversary of the third Shia Imam, Imam Hussein (AS).
Each year, a huge crowd of Shias flock to Karbala, where the holy shrine of Imam Hussein (AS) is located, to perform mourning rites.
In the past few years, around 20 million pilgrims from all over the world took part in the mourning ceremonies in the Iraqi holy city marking Arbaeen.
Arbaeen will fall on Saturday, October 19 this year.
The number of Iranians in this year’s Arbaeen pilgrimage is expected to exceed 3 million.