A wide-ranging cartel investigation is rocking Greece's two major ports, with authorities suspending six pilots, the harbour master of Thessaloniki and the chief pilot in Piraeus.

A total of 18 people were arrested as part of the probe, Greek police said in a statement, without identifying anyone by name. Several media reports and sources contacted by TradeWinds said that owners of four tug companies and the Thessaloniki harbour master are among them.

The suspects are accused of forming a ring that used extortion and fraud in connection with tug services at the northern Greek port, the police statement said.

According to a report by state-run Athens News Agency (ANA), the suspects were allegedly forcing shipping companies to pay money under the table to expedite ships' approach. Coastguards, pilots and tug companies also allegedly colluded to make approaching ships employ tug boats they did not need.

Sources with knowledge of the matter told TradeWinds that the probe began after complaints were made by a local tug company, which competitors forced out of business. Pilots and tug companies acting in cahoots with coastguards are said to have been fixing prices and abusing safety and port navigation rules to maximise employment time.

Thessaloniki is mostly known as a containership terminal.

Locals, however, said the investigation focused on small gas carriers approaching the nearby refinery of Hellenic Petroleum.

Greek authorities have sent pilots over from Piraeus to ensure smooth operations in Thessaloniki after local pilots were detained for questioning.

The investigation, however, is widening to Piraeus as well. Pilots there are said to have had their laptops and other records searched, a source said.

This was indirectly confirmed by a statement by Shipping Minister Ioannis Plakiotakis, who said he suspended the chief pilot of Piraeus for violating article 169 of Greece's criminal code. That article lays down a six-month jail term for disobedience to officials seeking legal assistance.

Greek Shipping Minister Ioannis Plakiotakis Photo: European People's Party

The affair has been uncovered by a new internal affairs unit within Greek police. The charges also coincide with the privatisation of the Thessaloniki port. A CMA CGM-led consortium took over control of the previously state-run Thessaloniki Port Authority (OLTH) last year.

OLTH’s new owner spent €232m ($254m) on a 67% stake in the company. Facing tough competition from other ports in the region, the consortium said it was planning to make even further investments to make the terminal able to host ships of up to 12,000 teu, up from the current 4,500 teu.

“No matter how this specific case will conclude, the way in which port navigation is conducted in our country needs to be reviewed,” OLTH said, according to media reports.