Washington (CNN) Two fathers who were separated from their children at the border are suing the US government for $12 million, saying their children were abused at foster homes in the US.

The lawsuit filed Friday in the US District Court of Arizona argues that the Trump administration's "zero tolerance" policy was "cruel and unconstitutional," that it tore their families apart and that their children are still suffering as a result -- more than a year after they were reunited.

The fathers also allege in the lawsuit that their children were abused by other children while in government custody.

In a statement released by the Southern Poverty Law Center, one of the fathers described the pain he said he and his family endured.

"He was taken from me and I had no idea what was happening to him. When I learned that he was abused by other boys, I was sick with grief," said the father, who's identified in the lawsuit by his initials, A.P.F. "No one deserves this cruelty."

Read More