The parents are members of the UK Independence Party, a right-leaning party that favors controlling immigration and withdrawing from the European Union.
The children are migrants from Europe.
Education Secretary Michael Gove said social workers had made “the wrong decision in the wrong way for the wrong reasons,” The Telegraph reported.
The local council – Rotherham Metropolitan Borough Council – pledged to probe the move.
“We are going to investigate to make sure everything has been done professionally,” council leader Roger Stone told Yorkshire Post.
According to the Post, an anonymous tip led social workers to the home, where three children 10 and younger lived.
Social workers said they were worried about the children’s “cultural and ethnic needs,” the Post said.
Joyce Thacker defended her department’s decision to BBC. She said she couldn’t ignore UKIP’s “very clear” anti-immigration policies.
“I have legal advice I have to follow for the placement of children and I was criticized before for not making sure their cultural and ethnic needs were met,” Thacker told BBC.
“If the party mantra is, for example, ending the active promotion of multiculturalism I have to think about that.”
The foster mother – with about eight years’ experience taking in children – told BBC she encouraged the children to speak their native language.
“We enjoyed singing one of their folk songs in their native language,” she said. “Having been told of the religious denomination of these children – we took steps to ensure that a school of their denomination was found.”