SEOUL, South Korea — South Korea said Saturday that it was trying to track down presumed kidnappers who may have abducted three South Korean nationals who had been working on a fishing boat in waters off Ghana.

Seoul's Foreign Ministry said the supposed kidnappers appear to have hijacked the boat on Tuesday and steered it toward the waters of Nigeria before using a speed boat to move the three South Koreans elsewhere.

The ministry said it didn't know where they went.

South Korea's military dispatched its anti-piracy Cheonghae Unit to the area after South Korean President Moon Jae-in ordered government officials and the military to invest full efforts to secure the South Koreans' "safe return," the ministry said.

Seoul is working with the governments of Ghana, Nigeria, Togo and other neighboring countries as well as the United States and the European Union to track down the South Koreans and their supposed kidnappers, it said.