"The embassy is at work. Everyone is at work. All services, all channels are active. We are in a close contact with Iranians," Mikhail Bogdanov told reporters.
The Iranian military captured the Stena Impero oil tanker in the Strait of Hormuz last Friday for allegedly flouting maritime rules. Its crew of 23, including three Russians, remain on board the ship, which is anchored in the Iranian port of Bandar Abbas.
The Swedish owner of the tanker, Stena Bulk, said over the weekend it had submitted a formal request with the port authorities asking to meet with the sailors and is waiting for a response. Iran says they are in good health.