Simon Cowell has praised "true professional" Mel B after it was revealed she would be entering rehab.

The Spice Girls star, full name Melanie Brown, confessed she would be seeking treatment for post-traumatic stress disorder (PTSD) after reaching "crisis point", and would be flying from the U.S. to the U.K. following the conclusion of this season's America's Got Talent.

Her judging panel colleagues leapt to her defence following the news, and head judge Simon said he had a "lot of respect" for the 43-year-old singer and presenter.

"Mel's a trooper... she comes to the show, leaves everything behind, focuses on the contestant. That is a true professional," he told Entertainment Tonight. "She's so professional, it's all about the contestants with her, so a lot of respect for her."

In the latest live episode of America's Got Talent, Mel made no reference to her decision to enter rehab, or her struggle with PTSD.

"She’s a very strong, wonderful lady whose battled what a lot of people battle," fellow judge Howie Mandel told ET after the show aired. "She's a friend and I think we have to be there for our friends and people we admire. And she's certainly someone I admire and whatever she wants from me and needs from me, I'm there for her."

Model Heidi Klum shared similar sentiments, and said of the mother-of-three: "I'm her friend and I've been her friend for a really long time and I'm always going to be there for her and help her with whatever she needs help in."

In an interview with The Ellen DeGeneres Show, which will air on Wednesday (29Aug18), Mel explained that her PTSD stemmed from her father's death last year, and her bitter divorce from ex-husband Stephen Belafonte.

"I've been in therapy since my father got diagnosed with cancer nine years ago," she told guest host Lea Michele. "My therapy changed a little bit because I was in a very intense relationship... I was with the same person for 10 years and that was quite a turmoil, very intense."