A bomb explosion in the south-eastern Iranian city of Chabahar has killed dozens of people and injured many more, Iranian news sources say.
The blast, said to be a suicide attack, took place outside the Imam Hossein Mosque, the Irna news agency said.
Irna said the governor-general of Sistan-Baluchistan province had confirmed the incident.
The province is prone to unrest, with the mainly Sunni population often claiming discrimination by Shias.
The attack reportedly targeted pilgrims marking Ashura, the Shia day of mourning for the martyrdom of a grandson of the Prophet Muhammad.