Somali pirates have released a chemical tanker ship and its 28-member North Korean crew.
The European Union's anti-piracy naval force says the MV Theresa VIII was freed Tuesday, after payment of a ransom.
Andrew Mwangura of the East African Seafarers Assistance Program says the ransom was about $3.5 million.
The ship had been seized nearly four months ago northwest of the Seychelles islands.
Meanwhile, the EU anti-piracy force says it has detained 17 suspected pirates in operations in the Indian Ocean since Friday.
The force says it captured nine men and destroyed a pirate "mother ship" in one incident Friday. It says it captured another eight suspects on Saturday.
European naval forces have recently intensified their efforts against the Somali pirate threat.
French naval forces detained 35 suspected pirates earlier this month. Captured pirates are usually turned over to regional governments for prosecution.
Somali pirates have hijacked dozens of ships over the past few years. Owners often pay multi-million-dollar ransoms to free the ships and their crews.
Following the release of the MV Theresa VIII, the pirates are believed to be holding seven ships with more than 100 crew members.
Some information for this report was provided by AFP, AP and Reuters.