The Marathon, owned by Western Marine Transport NV, was seized on Thursday some 185 kilometers (115 miles) southeast of the Yemeni port of Mukalla, the Ukrainian Embassy in the Netherlands said.
"The crew consists of eight persons, all of them Ukrainians," the ministry said in a statement. The ship's operator, Cargadoor Amons & Co., has confirmed the reports.
The Ukrainian embassies in the Netherlands and Kenya have been instructed to investigate the incident and contact the ship owner and operator to aid the "swift release" of Ukrainian nationals, the statement said.
In a similar incident, a Ukrainian cargo ship was seized by Somali pirates in September 2008. The Faina with the crew of 17 Ukrainians, two Russians and one Latvian was only released in February after the pirates received a reported $3.2 million ransom.
The ship's Russian captain, Vladimir Kolobov died of a heart attack soon after the ship was seized.
Pirates are increasingly active in the waters off Somalia, which has no central government and no navy to police its coastline.
