The Sunni armed group Jaish-ul Adl has claimed responsibility for the assassination of a public prosecutor in Iran's southeast, media reports say.
Thursday's reports came a day after Mousa Nouri - prosecutor of the city of Zabol, which lies near the Afghan border in Sistan-Baluchestan province - was slain in a "terrorist attack," according to officials.
Jaish-ul Adl, the rebel group formed last year whose name means Army of Justice in Arabic, said in a statement Wednesday night that the killing was carried out in retaliation for a mass hanging last week.
"After the hanging of 16 innocent young Baluchis, the fighters decided to take revenge and kill a judicial official," read the statement posted on the group's website, jaishuladl.blogspot.fr.
Home to a large Sunni minority, the province of Sistan-Baluchestan has been the scene of fresh unrest in recent weeks.
The group carried out an ambush on Iranian border soldiers on October 25, killing 14 of them.
In response, the authorities in Iran executed 16 "rebels", eight Sunni fighters and eight drug traffickers.
Security forces later killed four rebels in a separate clash near Mirjaveh, a town close to the border with Pakistan, officials said last week.