The Latvian Foreign Ministry confirmed that the sailor's life is not in danger and that he was allowed to contact his relatives July 24.
The Stena Impero tanker was impounded with its 23 crew members, including a Latvian national, on board at the port of Bandar Abbas after the Islamic Revolutionary Guard Corps seized it on July 19.
Iran has detained the oil tanker on allegations of failing to respond to distress calls and turning off its transponder after hitting a fishing boat.
There are 18 Indians, including the captain, three Russians, a Latvian and a Filipino on board.
The Latvian Foreign Ministry has submitted a note to the Iranian Embassy in Stockholm calling on Iran to release the Latvian citizen.
The Latvian national, a man born in 1978, is the chief assistant of the ship's captain.
