Nigerian security forces have been battling armed groups in different parts of the country. Photo: AP

Two South Koreans kidnapped by gunmen in Nigeria earlier this month have been released safely, Seoul's foreign ministry said on Saturday.

The two men were taken after gunmen ambushed their convoy in Nigeria's oil-producing Niger Delta on Dec. 12, killing four soldiers guarding the group and two civilian drivers.

"On Friday, we secured custody of the two abducted Korean citizens," the ministry said in a statement.

"Both people are currently in good health, and after a hospital checkup, they moved to a safe area and spoke with their families."

Volatile region

There are no details about how the expatriates were freed.

Attacks by militants in the Niger Delta have dwindled over the years. But the region is volatile and suffers from crude oil theft and vandalism of pipelines, which has taken a toll on Nigeria's oil output.

Kidnappings for ransom by armed gangs are also common in Nigeria with locals and foreigners targeted. Victims are often released by captors after ransom payments.

The Nigerian authorities have been trying to tackle the problem with massive deployment of security forces across the country.

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TRT Afrika and agencies