0810 GMT January 18, 2019
Ardeshir Yarahmadi, the head of the fisheries department of Iran’s Bushehr Province, said the three fishermen were arrested in June 2017 after their boat drifted into the Saudi waters.
They had been freed this week after “negotiations between foreign ministry officials of both countries”, Yarahmadi said, without giving the date of their release.
In February, Saudi Arabia freed nine Iranian fishermen detained for two years, accusing them of entering its waters.
Saudi authorities could not immediately be reached for comment.
Recently, Saudi Arabia agreed to issue visa to an Iranian diplomat to head the Islamic Republic's interests section in the kingdom, in a rare move after the two countries broke off relations two years ago.
Observers see the move as a positive diplomatic step in Tehran-Riyadh relations.
Relations between Iran and Saudi Arabia first soured after a deadly human crush during the Hajj rituals in September 2015, when hundreds of Iranian pilgrims among others lost their lives.
Tensions further escalated a few months later following the kingdom's execution of prominent Shia cleric, Sheikh Nimr al-Nimr.
Riyadh cut off diplomatic ties with Tehran in January 2016 following angry protests in front of its diplomatic premises in the cities of Tehran and Mashhad against the execution.