Sam Smith has pulled out of the Billboard Music Awards after suffering vocal strain.

The 'Like I Can' hitmaker is now unable to perform at the annual award ceremony, which is taking place at the MGM Grand Garden Arena in Las Vegas on May 1.

A statement on his Twitter reads: ''In the wake of cutting his South African tour short last week, Sam's medical specialists are requiring him to have further rest. 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 apologise for the disappointment for those affected, but the primary focus at this time needs to be on Sam's recovery and health.''

Sam was due to perform several concerts in Cape Town, South Africa last week but he had to stop part way through the first show and then went on to cancel the rest.

Sam underwent surgery in 2015 on his haemorrhaged vocal cords.

In a statement, Massachusetts General Hospital, which treated the star, said at the time: ''Sam Smith underwent vocal cord microsurgery by Steven Zeitels, MD, to stop recurrent vocal cord haemorrhage (bleeding). This condition is the result of unstable blood vessels in the vocal cord that can rupture and prevent vocal performance.

''Sam came to Boston to consult and undergo corrective voice surgery with Zeitels, the director of the Massachusetts General Hospital Voice Centre. Zeitels, who is also the Eugene B. Casey Professor of Laryngeal Surgery at Harvard Medical School, has pioneered many vocal cord surgery procedures for benign and malignant problems including the use of specialised lasers to stop vocal cord bleeding in singers. He has performed this unique procedure for many vocalists - including Steven Tyler, Lionel Richie, and Adele - allowing them to return to full performance. Similarly, Zeitels expects Sam to make a full recovery from his laser microsurgery.''