Kristin Cavallari's brother reported missing in Utah

Kristin Cavallari in New York City ( Steve Mack/Getty)

The brother of reality television star Kristin Cavallari has reportedly been missing for more than a week.

Law enforcement officials in Utah have called the circumstances “suspicious” as Michael Cavallari’s 2014 Honda Civic was found abandoned on Interstate 70 just days after Thanksgiving.

Ms Cavallari thanked her fans on Monday for their ongoing support throughout the open missing persons investigation.

The Grand County Sheriff's Office reportedly became aware of the situation on November 27. Grand County Sheriff Steven White said that Mr Cavallari's car may have collided with a rock on the side of the road.

"We're combing the area for anything we can find," White told KSL.com. "We're deeming it suspicious, but there's nothing to indicate anything one way or another. The vehicle was just abandoned."

 

I appreciate all the concern, thoughts, and prayers that have been extended to me and my family. We remain hopeful and I will share any news that we receive. I have such gratitude for all those that have shared their support.

A photo posted by Kristin Cavallari (@kristincavallari) on Dec 7, 2015 at 7:33am PST

Mr Cavallari was last seen wearing a green sweatshirt, jeans and black shoes, Sheriff White said, according to KSL.com.