United Kingdom, June 19 -- Oliver Tree's mother has paid tribute to her son following his tragic death.

The 32-year-old singer was one of six people killed in the mid-air collision between two helicopters in Rio de Janeiro, Brazil, earlier this month.

Tributes have been flooding in from those in the showbiz world, as well as friends and family, with Oliver's mother Christine Begin Nickell the latest to share a heartbreaking post remembering her son.

Sharing a childhood picture of Oliver on Facebook, she wrote alongside it: "Our dear son Oliver, you made this world a better place. We are so proud of you. RIP."

Christine's Facebook post came after Oliver's ex Melanie Martinez, who dated the Miss You singer after years of friendship, too...