Singer Justin Bieber has refuted an allegation that he sexually assaulted a woman in 2014, saying he doesnt take "sexual abuse lightly".

He also provided evidence in the form of receipts, emails, social media and press reports, reports variety.com.

A woman posted from an anonymous Twitter account, claiming that the alleged assault happened at a hotel in Austin on March 9, 2014, when Bieber made a surprise appearance at the South By Southwest music festival.

Reacting to the allegations, Bieber wrote on Twitter: "I don't normally address things as I have dealt with random accusations my entire career but after talking with my wife and team I have decided to speak up on an issue tonight."

"Rumours are rumours but sexual abuse is something I don't take lightly. I wanted to speak out right away but out of respect to so many victims who deal with these issues daily I wanted to make sure I gathered the facts before I made any statement," he added.

Bieber wrote "there is no truth to this story" and provided emails, receipts and articles showing that he stayed at an Airbnb on the night of the alleged assault and at another hotel the next night. The singer says he stayed with his then-girlfriend, Selena Gomez, and their friends at the time.

Bieber shared that it is impossible that the alleged incident took place, and added that he plans to take legal action against the claim.

"Every claim of sexual abuse should be taken very seriously and this is why my response was needed. However this story is factually impossible and that is why I will be working with twitter and authorities to take legal action," he wrote.