The pirates took the four South Koreans into Somalia after abandoning the MT Gemini and freeing 21 non-Korean crew members, the official at Seoul's foreign ministry told journalists on condition of anonymity. They have called for the release of five other Somali pirates who were captured in a South Korean naval operation earlier this year and were sentenced to long prison terms in an unprecedented move to punish foreign pirates. Navy commandos raided a hijacked South Korean ship in January, rescuing all 21 crew members, killing eight pirates and capturing five others. The five were brought to South Korea for trial and sentenced to terms ranging from 13 years to life in prison. "The pirates (on the MT Gemini) have demanded compensation from our government for their colleagues who were killed and called for the release of those put on on trial," the official was quoted as saying by Yonhap news agency. "We do not negotiate with pirates and we are closely in touch with the Singaporean firm to secure the release of the remaining four," he said. The MT Gemini, owned by Glory Ship Management, was carrying 28,000 tonnes of crude palm oil from Indonesia to Kenya when it was hijacked on April 30 and diverted towards Somalia. The ship had 13 Indonesians, three Myanmar nationals, five Chinese and four South Koreans on board. The pirates left the ship at the Somali port of Hobyo soon after the Singaporean firm dropped an undisclosed sum in ransom from a helicopter, the foreign ministry official was quoted as saying.