Justin Bieber reportedly donated $545,000 (£340,625) to Aids charities at a gala in Cannes on Thursday (22May14)

The Baby hitmaker attended the amfAR Cinema Against Aids bash at the Cannes Film Festival along with other celebrities including event host Sharon Stone, Heidi Klum and Leonardo DiCaprio, who auctioned off a trip into out of space with him at the annual auction.

Sources tell Tmz.com that Bieber watched as one guest pledged $545,000 (£340,625) to the charity before quietly announcing that he would match the donation.

Staff reportedly checked with the singer, who confirmed he was certain he wanted to give the huge amount.

Bieber subsequently took to his Twitter.com page and wrote, "Amfar #giveback."