Greek officials were investigating on Monday whether 680 tons of explosives found on a ship seized off the coast and bound for Tunisia were destined for a terror organization. Bomb experts started examining the cargo and the Baltic Sky's seven crew were due to be questioned by a public prosecutor later in the day, officials said. Authorities were checking paperwork to see whether the cargo was registered as explosives or labeled as something else. "We need to check if the cargo is legal or if it was bound for any terrorism group," a Merchant Marine Ministry official told Reuters. "The army's bomb squads are checking the explosives found on the ship and the crew members and the captain will go to the public prosecutor later today to testify." The crew comprised five Ukrainian nationals, including the captain, and two Azeris. Elite troops stormed the Comoros-flagged Baltic Sky sailing in western Greek waters late on Sunday after receiving a tip-off it was carrying suspicious cargo in its holds. A police spokesman said the ship was carrying ammonia dynamite, an explosive widely used in mining, as well as detonators and fuses. Tunisia has a significant mining industry. **FLAG OF CONVENIENCE*** The discovery comes amid heightened security after a series of bombings in Saudi Arabia and Morocco, and a fresh terror warning in Kenya. Although it is not yet clear whether the cargo is legal or illegal, authorities hailed the operation as a major success. "It looks certainly like a suspect ship," government spokesman Telemachos Hytiris told Reuters. "This is a huge amount of explosives and a great success for Greek authorities." He said all international police and intelligence services were immediately notified of the operation and the haul. The Merchant Marine Ministry official said the vessel, berthed at the western Greek port of Platiyali near the seaside town of Astakos, was heavily guarded by police and coast guards. "We saw the ship outside the port yesterday and I alerted the coast guard," Astakos mayor Pythagoras Samaras told Reuters Television. "The ship looks old and the crew members were asking for supplies. Maybe it had lost its route." Greece has increased collaboration with international police forces ahead of the 2004 Athens Olympics and has beefed up coast guard patrols off its shores to stem a growing flow of illegal immigrants. NATO forces have also been boarding ships in the eastern Mediterranean over the last few months as part of the U.S-led "war on terror." The Comoros flag is considered a flag of convenience. Shipping sources said the Baltic Sky began its journey in the Black Sea in early June and had been heading toward the Tunisian port city of Gabes. The Merchant Marine Ministry said it was owned by a Marshall Islands registered company named Alpha Shipping Inc. **PHOTO CAPTION*** Athens, Greece