Australian Open champion Serena Williams has pulled out of this week's Dubai Tennis Championships, organisers said on Saturday.

Officials released a brief message on Twitter saying Williams and Canada's Genie Bouchard had withdrawn from the lucrative WTA event.

Williams recently won her sixth Australian Open title but the world number one sat out last week's Fed Cup tie for the United States because of a persistent, nagging cough.

No reason was given for Bouchard's withdrawl, after she was awarded a wild card in the event.

Venus Williams won the title last year and will be defending her crown at Feb. 15-21 tournament.