(Reuters) - The U.S. Department of Homeland Security’s acting secretary, Kevin McAleenan, has ordered an investigation into reports that border patrol agents have been posting offensive anti-immigrant comments and threats against lawmakers in a secret Facebook group.

“Reporting this week highlighted disturbing & inexcusable social media activity that allegedly includes active Border Patrol personnel,” he wrote on Twitter on Wednesday, calling the reported comments “completely unacceptable.”

He said any employee found to have “compromised the public’s trust in our law enforcement mission will be held accountable.”

(The story corrects day of the week in 2nd paragraph to Wednesday from Monday )