However, there was no indication of how many of the five border guards had been released after Jaish-ul Adl, which operates in southeastern Iran, claimed last month to have executed one of them.
"The soldiers were handed over some hours ago by the small terrorist group Jaish-ul Adl to Iranian representatives in Pakistan," said the Fars news agency, quoting an unidentified security official.
For its part, Jaish-ul Adl announced the releases on its Twitter account.
The five soldiers, who were serving their 24-month mandatory military service, were abducted in the restive southeastern province of Sistan-Baluchestan, where Shiite-majority Iran has been confronting the Jaish-ul Adl Sunni rebels.
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Last month the group announced it had executed one of the five, Jamshid Danayifar, and warned of more executions to come unless Iran freed Sunni prisoners.
The Iranian authorities immediately denied the execution claim, insisting that all five soldiers were alive.
The guards are believed to have been taken into neighbouring Pakistan after being kidnapped on February 6.
Border guards chief Hossein Zolfaghari has admitted that there was "negligence" in the lead-up to the kidnapping, saying those responsible were suspended, with some facing prosecution.
Jaish-ul Adl took up arms in 2012 to fight for what it says are the rights of Iran's minority Sunni population.
Sistan-Baluchestan, which is home to a large Sunni minority, has been the scene of unrest in recent years fuelled by its alleged marginalisation by the predominantly Shiite Islamic republic.