Jihadist separatist group Ansar al-Furqan has claimed responsibility for Thursday's assault in which an explosives-laden car was driven into a police station in the port city of Chabahar.
The authorities have rejected the claim of responsibility for the attack, relatively rare in Iran, which also injured around 40 people.
Police chief Hossein Ashtari said 10 people had been arrested, according to the conservative Fars news agency, without giving any details.
Ansar al-Furqan released a photo of the alleged suicide bomber on Saturday, identified as Abdullah Aziz, according to the Site Intelligence Group, which monitors jihadist activities.
Sistan-Baluchistan province has faced decades-long insurgencies by Pakistan-based Baluchi separatists and Sunni Muslim extremists.
Iran has blamed the United States and Tehran's regional rivals, Saudi Arabia and Israel, for supporting the insurgent groups.
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