The Greek government and shipping industry on Thursday called for a global mobilization to free the crews of two oil tankers held by Iran in an ongoing dispute with Athens.

“We call on all nations to act in order to end this unacceptable incident, and to ensure it does not happen again,” Merchant Marine Minister Ioannis Plakiotakis told reporters.

Iran’s Revolutionary Guards on Friday seized the two Greek-flagged tankers in the Gulf, days after Athens said it would deliver to Washington Iranian oil it had seized from a Russian tanker in April.

Plakiotakis said last week’s incident posed a “threat” to shipping safety and trade and has “cast a shadow” over Greece’s top shipping fair Posidonia, which opens Monday with over 1,900 companies from nearly 90 nations participating.

Speaking at the Posidonia inaugural press conference on Thursday, Union of Greek Shipowners president Melina Travlos said some of the sailors held by Iran were youths on their first shipping assignment.

“The global shipping community must mobilize, nations, everyone. This situation needs to end,” she said.

Greece’s coastguard on Thursday said both ships are moored at the Iranian port of Bandar.

The coastguard has identified nine Greeks and a Cypriot on board, but has given no information about other crew nationalities.

Iran has said the crews of two tankers were in “good health” and not under arrest.

The Revolutionary Guards — the ideological arm of Iran’s military — had said it seized the tankers “due to violations”, without elaborating further.

Greece has condemned Tehran’s detention of the two ships as “tantamount to acts of piracy” and warned its citizens not to travel to Iran.

The German and French foreign ministries, in separate statements, condemned the seizure as a violation of international law, and called on Iran to immediately release the ships and their crews.

The United States has also strongly condemned Iran’s seizure of the two tankers, and demanded their immediate release.

Iran has called the statements “one-sided” and “inappropriate interference.”

Tehran noted that France and Germany “are protesting against the legal measures taken in Iran” while “remaining silent” on Greece’s own seizure of the tanker, which it said was Iranian.