Speaking at a press conference on Wednesday, Hossein Zolfaqari, head of the Arbaeen Task Force, announced that around 900,000 Iranians have signed up so far to get a visa and travel to Iraq on Arbaeen.
The Arbaeen mourning ceremony is one of the largest religious gatherings in the world.
It marks the 40th day after the martyrdom anniversary of the grandson of Prophet Mohammad (PBUH), Imam Hussein (AS).
Each year, pilgrims, mainly from Iraq and Iran, travel long routes on foot to Karbala, where the holy shrine of Imam Hussein (AS) is located.
Elsewhere in the press conference, Zolfaqari said the Iraqi government is responsible to ensure security of the pilgrims in the Arab country.
While Iraqis are scheduled to conduct aerial surveillance of some areas to ensure security, Iran will provide them with advisory assistance during the pilgrimage, he explained.
Last year, around 20 million pilgrims from all over the world gathered in Karbala to attend the mourning ceremonies marking Arbaeen.