Sam Smith has pulled out of the Billboard Music Awards over vocal chord fears.

The singer was due to perform at the awards ceremony next week but has had to cancel over vocal strain. Smith also cut short his South African tour last week, as well as the Azerbaijan Grand Prix, on the advice of his medical specialists. “In the wake of cutting his South African tour short last week, Sam’s medical specialists are requiring him to have further rest," a statement from Smith's team read. “Regrettably this means he will be unable to perform at the Azerbaijan Grand Prix in Baku this weekend or the Billboard Music Awards in Las Vegas next week. "We apologize for the disappointment for those affected, but the primary focus at this time needs to be on Sam’s recovery and health.” https://www.instagram.com/p/BwP_aRwgyEN/ The Sun reports that Smith underwent vocal surgery four years ago, and that the Grammy winner is fearful that he will continue to do his voice more damage. A source told the publication that Smith's vocal chords are under serious strain and that is he now working with specialists to see how best to move forward. “He had surgery on his vocal cords four years ago but he’s keen to try to avoid going under the knife again," they said. “Sam has enlisted the help of vocal experts and is doing everything he can to recover. He’s not going to rush anything and said he’ll wait for as long as it takes to get well again. This is a huge worry for Sam and his team but they’re staying positive.” Normani, who collaborated with Smith on 'Dancing with a Stranger' has also been forced to cancel her Billboard performance.