Hip-hop star Lizzo says members of her crew were subjected to an assault by a "bigoted" security guard at a festival in Wisconsin Thursday night.

The Minneapolis artist was performing at Summerfest in Wisconsin, but says the experience was tainted by an incident involving some of the event's security staff.

But as she explained on Twitter, while she was on stage, a security guard "slapped and manhandled my hair stylist and stylist" after tackling them to the ground in what she says was a bigoted and racist incident.

In response, SummerFest issued the following statement: "Lizzo gave an incredible performance which she now feels is tarnished by events which occurred during the performance. We do not tolerate racism in any form. We will conduct a thorough investigation.

"We have an experienced crowd management staff who strive to protect performers and fans. While there may be challenges during a performance, we expect those challenges to be handled professionally & respectfully.

"If those standards were not met, we will take appropriate action."

Lizzo initially uploaded video of the guard alleged to have carried out the assault, but has since deleted the tweet.

The "Juice" singer is now headed to the U.K., where she will be performing at the legendary Glastonbury Festival.