BERLIN (AP) — Two men were arrested Tuesday on suspicion of attempted sabotage against ships being built for the German navy in Hamburg, authorities said.

The suspects were detained in the German port city and in an unidentified village in Greece, Hamburg prosecutors said in a statement. They didn’t name the 37-year-old Romanian and 54-year-old Greek suspects, but said their apartments in Hamburg, Romania and Greece were searched.

The two men, who worked at the port of Hamburg, are suspected of attempting to sabotage several corvettes destined for the German navy at a shipyard in the city last year. Prosecutors said they are accused of dumping more than 20 kilos (44 pounds) of abrasive gravel into the engine block of one of the ships, puncturing fresh water supply lines, removing tank fuel caps and deactivating electronic safety switches.

If the sabotage hadn’t been discovered, it could have caused significant damage to the ships or delays to their departure, with a potential impact on national security, prosecutors said.

Prosecutors said they are still reviewing evidence and the investigation will also address the question of who might have ordered the sabotage.