A former University of Wisconsin-Madison graduate student of Indian-origin was arrested after threatening students and staff at his alma mater with an email saying he planned to hide the flesh of their children in hamburger meat, according to media reports.

Arvin Raj Mathur, 32, of Grass Lake in Jackson County, was arrested on Friday at Detroit Metropolitan Airport and he is being temporarily held without bond, The Detroit News reported.

Mathur is being held temporarily without bond in St. Clair County Jail and awaiting a detention hearing on Tuesday in a federal court in Detroit.

A former graduate student in the Department of Anthropology, Mathur is charged with interstate or foreign threat to injure after authorities say he emailed threats from outside the US to nine Wisconsin residents, according to court records.

After being charged with emailing threats to nine people, he made a brief appearance in federal court on Saturday.

Among those emails were one to an anthropology professor saying that two of the other people he had threatened should "sue me right away," authorities said.

"Otherwise, I will murder their children. Call the police and a lawyer, otherwise, I will kill their children and hide their flesh inside of their burger meat," he added in the email, court records show.

He has also been accused of sending another email to an assistant professor of the college with the subject line, "We are going to kill your daughters." That person told officials that "he found the email disturbing and he was scared for his family's safety," according to court records.

"Mr Mathur is presumed innocent, and we'll await future proceedings to comment further," his defence lawyer, Amanda Bashi, wrote in an email to The Detroit News.

There was no immediate comment from a University of Wisconsin-Madison spokesman on Sunday.