The Iranian military has intercepted two Greece-flag suezmaxes that were underway off Iran on Friday, sparking severe diplomatic protests by the government in Athens.

Shipping sources told TradeWinds that one of the vessels in question is Delta Tankers' 157,400-dwt Delta Poseidon (built 2011).

The second vessel is Polembros's 150,000-dwt Prudent Warrior (built 2017).

According to one source, six Iranian soldiers landed on board the Delta Poseidonby helicopter as it was travelling 22 nautical miles (41 km) off the Iranian coast.

The crew of the ship was ordered to assemble on the bridge for questioning, the source said.

The incidents are ongoing at the time of writing. The Delta Poseidon and the Prudent Warrior were led towards Iranian waters and are moored there.

The Delta Poseidon is said to be laden with a cargo of crude from Basrah, Iraq, en route to the Agioi Theodoroi refinery in Greece.

The owner of one of the ships is said to have had no contact with the crew for at least three hours. One source familiar with events said that it was not clear yet if this will be a brief detention or whether the matter will drag on for longer.

The exact number of the two ships' crews remains unknown. According to the Greek foreign ministry, however, they include nine Greek citizens.

In a statement issued later on Friday, the ministry called the Iranian action “an effective act of piracy” and called for the immediate release of the ships and their crews.

“These actions will have particularly negative consequences on bilateral relations, as well as on European Union-Iran relations,” the foreign ministry said.

Iranian payback

According to Iranian media, responsibility for the seizure was claimed by the Islamic Revolution Guards Corps (IRGC), the Iranian regime's elite military organisation.

“The IRGC navy today [Friday] seized two Greek oil tankers for violations they have carried out in the waters of the Persian Gulf,” the IRGC said in a statement cited by the Mehr News Agency.

It looks very probable that the Iranian move is meant as an instant reprisal against Greek authorities after they allowed the transfer to the US of an Iranian oil cargo that was on board the Iranian-flagged 115,400-dwt aframax Lana (built 2013).

The Lana, previously known as Pegas, had been seized by Greek authorities in April because the ship was said to be in violation of sanctions against Russia. The ship had been stuck in Greek waters after an engine failure.

Iranian authorities railed against the Greek authorities’ decision, describing it as being part of an “international robbery”.

“The Islamic Republic of Iran will not waive its legal rights and expects the Greek government to adhere to its international obligations in the field of seafaring and shipping,” the Ports & Maritime Organisation of Iran said on its website.

This sequence of events is reminiscent of another incident in 2020, when Iranian military forces briefly boarded a Greek-controlled ship a few days after another tanker under the same managers had allowed the transfer to the US of an Iranian gasoline cargo that was originally heading towards Venezuela.