The children lived cramped in a cell with many other women, with little to eat, in an environment ill-suited for children.
The group interviewed 340 people for the report, including 270 workers from 73 different factories in and around Phnom Penh.
Cambodia has seen a wave of recent labor unrest and authorities have violently crushed protests.
In 2001, waves of Montagnard asylum-seekers found their way to Cambodia, and many of them were later received by the United States.
Koul Panha, executive director for Comfrel, told VOA Khmer on Monday that more than 60 NGOs disagree with the reforms, especially prohibitions on speech.
U.S. President Barack Obama and former president George W. Bush participated Saturday in the 50th anniversary observance of the beating of peaceful civil rights demonstrators by police in Selma, Alabama.
U.S. President Barack Obama marked the 50th anniversary of two Selma-to-Montgomery voting rights marches Saturday with a call to Americans to work together to make the country better. Michael Brown from Washington DC.
On International Women's Day, four women share their view on women's rights and women's empowerment via VOA Khmer.
A total 45 known Montagnards—an ethnic minority in Vietnam that claims persecution there—have been arrested and deported since December.
Supporters say Meach Sovannara is being held for political purposes and for his support of the Cambodia National Rescue Party.
Domestic violence remains a prevalent problem in post-war Cambodia, with more than 20 percent of men reportedly committing physical violence against women, according to the rights group Licadho.
The 13, including one woman, had fled to the jungles of remote Ratanakkiri province late last year and were brought to Phnom Penh with the support of the UN High Commission for Refugees.