"The Iranians have been kept by the pirates for five years," the Iranian intellgence ministry said.
It pointed out that that the three Iranians were from Baluch tribe in the Southeastern part of the country.
Their Iranian fishing vessel had been captured in March 2015.
Piracy used to be a major problem in the Gulf of Aden as Somali pirates frequently attacked ships, seized their cargoes and kidnapped crew members, later demanding ransom for their release. Over the past years, the threat has largely subsided after international warships were deployed to the area to protect vessels.
The Iranian Navy has been conducting anti-piracy patrols in the Gulf of Aden since November 2008, when Somali raiders hijacked the Iranian-chartered cargo ship, MV Delight, off the coast of Yemen.
According to UN Security Council resolutions, different countries can send their warships to the Gulf of Aden and coastal waters of Somalia against the pirates and even with prior notice to Somali government enter the territorial waters of that country in pursuit of Somali sea pirates.
The Gulf of Aden – which links the Indian Ocean with the Suez Canal and the Mediterranean Sea – is an important energy corridor, particularly because Persian Gulf oil is shipped to the West via the Suez Canal.