A teacher in the U.S. state of Texas reported a non-communicative 6-year-old Muslim boy with Down syndrome to the police for alleged "terrorism," leading to an investigation of the boy's family.

A probe was launched after the teacher claimed Mohammad Suleiman was repeating "Allah" and "boom" in the classroom.

His parents said the accusation is impossible, given that Mohammad "doesn't speak at all" and has "the mental capacity of a 1-year-old."

"Mohammad was born with Down syndrome Chromosome 21. He needs care all the time," Maher Suleiman, the boy's father, told Fox26 news.

"They claim that he's a terrorist. This is so stupid, this is discrimination actually. It's not implied discrimination, it's a hundred percent discrimination."

The family has gone through exhausting investigations from police and social services, said the boy's father, Maher Suleiman.

"The last three or four weeks have been the hardest of my life," he told Fox26 news. "My wife and kids were crying a few days ago, and I told them everything is fine.

The teacher who called in the allegations was covering for a staff member at CJ Harris Elementary School in Pearland, about 30 km south of Houston.

While the Pearland Police Department has concluded its probe without action, Child Protective Services maintains an open investigation.

Islamophobia has been on the rise in the U.S. in the past several years, boosted by the election of Donald Trump as president and his discriminative political rhetoric, as well as the media bias against Muslims and Islam.

According to the Council on American-Islamic Relations (CAIR), "the number of hate crimes in the first half of 2017 spiked 91 percent compared to the same period in 2016."