Three seamen held hostage for about three weeks after pirates attacked their tanker off Nigeria have been freed and will be repatriated, the ship's management company says.

The men, two Greeks and a Pakistani, are currently undergoing medical examinations and receiving treatment in Nigeria, Aeolos Management said Wednesday.

They were abducted on Feb. 3, when unidentified gunmen attacked the Maltese-flagged Kalamos tanker off Nigeria, killing the first officer.

Aeolos Management said it would not release any information on how the captives' freedom was obtained, to avoid encouraging future attacks of the sort.

Shipping companies are often forced to pay ransoms to free vessels and crews from pirates' hands, but rarely make any details public.