Rome: Migrants have hijacked a merchant ship that rescued them off the coast of Libya and is now heading towards Malta, Italian Deputy Prime Minister Matteo Salvini and Maltese authorities say.

Italian Interior Minister Matteo Salvini. Credit:AP

The 108 migrants were picked up by the Turkish cargo ship Elhiblu 1 and they hijacked the vessel when it became clear that it planned to take them back to Libya, according to the website of Italian daily Corriere della Sera and Italian news agencies.

"These are not migrants in distress, they are pirates, they will only see Italy through a telescope," said Salvini, who has cracked down on illegal immigration, including closing Italy's ports to charity ships, since he took office in June last year.

A spokeswoman for Malta's armed forces confirmed the ship had been hijacked and said Maltese authorities were monitoring its progress and it would not be allowed to dock in Malta.