Somali pirates hijacked a German-owned tanker carrying liquefied petroleum gas on Thursday.
It was the first ship to be seized in the Gulf of Aden since 3 January.
The Longchamp was hijacked with a crew of 12 Filipinos and one Indonesian en route from Europe to the Far East.
Hamburg-based ship operator Bernard Schulte Shipmanagement confirmed the hijacking. It said no demands had been made.
Liquefied petroleum gas is highly flammable.
Attacks by Somali pirates have raised insurance costs, prompted some owners to go round South Africa instead of via the Suez Canal.