U.N. special envoy on North Korean human rights Marzuki Darusman in May said he was concerned about the status of the defectors.
The federation, known by its French initials FIDH, said it was able to confirm through North Korean human rights channels the defectors were handed over to the North Korean Embassy in Vientiane, the Laotian capital.
"International law requires that a person be allowed to apply for asylum and not be expelled to a country where his life or freedom may be under threat," FIDH said in a statement Thursday.
The federation said nearly 25,000 North Koreans have fled the north since the Korean War stalled in the 1950s. Most of them escape through China or other countries in Southeast Asia before making their way to Seoul.
Advocacy groups have expressed concern over North Korean human rights issues. Thousands of North Koreans spend their lives in forced labor, though human rights group say the issue is sidelined because of security concerns related to North Korea's nuclear weapons program.
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