ABUJA: An arrested gang leader told Nigerian authorities that South Korean firm Hyundai Heavy Industries paid a 30 million naira ($192,100) ransom to release six workers kidnapped in Nigeria's oil region last month, police said on Friday.

Gunmen kidnapped four South Korean and two Nigerian men at a Hyundai Heavy building on Dec. 17, in southern oil-producing Bayelsa state. They were released five days later.

Hyundai Heavy Industries was not immediately available for comment.

Kidnapping is rife in Africa's top energy producer, making millions of dollars a year for criminal gangs, especially in the heart of the oil industry, in the swampy Niger Delta.

Bayelsa state police commissioner Kingsley Omire confirmed the ransom figure paid and said they had caught most of the suspected kidnappers. But the leader of the criminal gang had escaped after being arrested, he said.

"He told us that they received a ransom of 30 million naira and his own share was 3 million naira, which he used in buying electronic devices, DVD players etc", Omire said by telephone.

"Following his confession that he has some arms in his house, he was followed to his house, but his men opened fire on our men in the waterways ... during the gun battle he escaped."

It is unusual for authorities to admit a ransom has been paid because they say it encourages abductions.

The 83-year-old mother of Finance Minister Ngozi Okonjo-Iweala was abducted on Dec. 9 in Delta state but was freed five days later, a high profile target that showed few are safe from the clutches of kidnappers in Nigeria.

Three Italians and five Indians kidnapped during two separate pirate attacks last month off Nigeria are still missing. ($1 = 156.2000 Nigerian naira)