South Korean, three Filipinos freed after captivity in Libya
The release of the hostages was mediated by the United Arab Emirates, which worked with the self-styled Libyan National Army led by commander Khalifa Haftar.
Since last month, Haftar's forces have been battling in western Libya, trying to take the capital of Tripoli and have been locked in heavy fighting in and around the city with militias loosely allied with a UN-supported government.
Several Arab countries, including the UAE and Egypt are backing Haftar.
The UAE's foreign ministry said the four hostages, who were held captive by unnamed armed groups in Libya, have been released thanks to "intensive efforts" made by the UAE in coordination with Haftar's forces.
The four are civilian engineers who were working at a desalination plant in Libya, the ministry said in a statement.
"Upon receiving requests from the Philippines and South Korea, the UAE communicated with the Libyan National Army to work on releasing them and to ensure their safety," the statement said.
South Korea's presidential office issued a similar announcement. Presidential national security adviser Chung Eui-yong said in a televised briefing that South Korea thanks the UAE government for the rescue efforts.
The UAE ministry said the four were airlifted to Abu Dhabi before being taken to their home countries.
Chung said the 62-year-old South Korean national surnamed Joo was freed after 315 days of captivity. An initial medical checkup showed Joo has no major health problems; he was to return home on Saturday.
Both UAE and South Korean announcements didn't provide details about how the hostages were set free or which armed groups held them.
The pro-Haftar Al Marsad news website reported on Friday that the hostages were moved from one "criminal gang" to another before Haftar's forces located and freed them. No other details were reported.
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