Captain Pak Hyeon contacted VOA by phone Friday, saying the pirates want Seoul to pay compensation for eight dead comrades and release another five held prisoner. He said the pirates have not named a price.
There was no immediate response by the South Korean government to those demands.
Somali pirates captured Pak and his crew aboard the MT Gemini off the Kenyan coast several months ago.
Pak said that the pirates are treating him and his fellow 24 crew members well and that they do not believe they are in any immediate danger. But he said they are fed only twice a day, kept inside aboard their ship and are homesick.
He also said he and three other crew members are being kept separate from the other hostages.
On Thursday, the London-based International Maritime Bureau — which monitors maritime affairs — said the number of pirate attacks off Somalia's coast rose to a record high during the first half of this year.
It also said the raids have grown increasingly bold and violent.
Somali pirates continue to terrorize shipping in the Indian Ocean and Arabian Seas despite international naval patrols.
The pirates have hijacked dozens of ships and made hundreds of millions of dollars from ransom payments in the past few years.