Arizona's education chief says the federal government has launched an investigation into whether the state discriminates against teachers who are nonnative English speakers.

The probe was launched by the U.S. Departments of Justice and Education. It's the most recent of several federal investigations aimed at Arizona, which has been in the spotlight for its law targeting illegal immigrants, Senate Bill 1070.

"It may be that the Senate Bill 1070 issue is causing some sort of campaign, I don't know, by the federal government against Arizona," State Superintendent of Public Instruction Tom Horne told The Arizona Republic.

The state Department of Education for years has been monitoring the fluency of teachers who instruct English learners. In April, the education department began instructing districts to fire teachers who weren't proficient in English.

Federal officials disclosed the investigation in a letter to the Arizona Attorney General's Office, Horne said.

Justice Department spokeswoman Xochitl Hinojosa in Washington, D.C. declined comment to The Associated Press on Wednesday. The U.S. Department of Education did not immediately return a call seeking comment.

Horne predicted the federal agencies will conclude the state has done nothing wrong.

"I'm sure they're going to find everything is fine," Horne said. "Teachers who are teaching English need to be fluent in English, and if kids can understand what they're saying, it's not an issue."

The state Department of Education has pushed a get-tough attitude on teachers who lack basic English skills or whose grammar is considered so poor that it could detract from a child's ability to learn.

Critics say the policy could eliminate talented teachers who have a positive influence on students struggling to learn English. Some believe the Arizona Department of Education singled out Latino teachers when it audited classes taught by bilingual teachers, criticizing them for pronunciation, grammar and not speaking English well.