Somali pirates seized control of a German-owned merchant vessel in the Indian Ocean on Sunday. It was the second hijacking on the high seas in two days.
It is not immediately clear how many crew were aboard the Beluga Fortune nor what it was carrying.
Earlier, an LPG tanker was hijacked off the coast of east Africa.
The MV York was seized at 5.30pm (local time) on Saturday off Kenya, less than 12 hours after leaving the port of Mombasa. The attack took place about 50 nautical miles offshore.
The Greek coastguard said the ship was carrying 150 tonnes of liquefied petroleum gas.
The vessel has a crew of 17, including a German master, two Ukranians and 14 Filipinos.
A fishing vessel, the Golden Wave, that was taken on 9 October, was seen in the vicinity of the tanker.
The EU said on Sunday that pirates were currently holding 20 vessels with more than 430 hostages.