There are 16 crew-members on board the ship apart from the captain, including 14 Filipinos and two Ukrainians.
"The crew is well. I can't say any more at the moment," Theagenis Sarris, a spokesman for the Interunity Management Corporation (IMC), told the news agency DPA on Sunday.
The pirates have not made any demands yet, Sarris said. "They usually do that a few days after the hijacking," he added. The York is currently being sailed towards Somalia, and Sarris said that the 68-year-old captain, described as "very experienced," had given the impression that he could not speak freely.
Negotiations are expected to last a long time. Another Greek shipping company recently paid hijackers €6 million ransom to get a ship back.
According to Singapore authorities, the York was attacked 90 nautical miles from Mombasa. An alarm signal was sent out in the afternoon. The ship was headed from Mombasa to Mahé, the largest island in the Seychelles.