Nick Kyrgios said that doping cases involving Grand Slam winners Jannik Sinner and Iga Swiatek are "disgusting" for tennis. 

Swiatek, currently world number two, faced a one-month suspension after testing positive for a banned heart medication in August, when she was ranked first in the world. 

World number one Sinner, meanwhile, tested positive for anabolic steroid clostebol twice in March and the Italian could also face suspension from the sport. 

"I just think that it's been handled horrifically in our sport," said Kyrgios.

"Two world number ones both getting done for doping is disgusting for our sport. It's a horrible look."

The 29-year-old was speaking ahead of his return to competitive action following an 18-month injury lay-off at the Brisbane International. 

"The tennis integrity right now, and everyone knows it but no one wants to speak about it, is awful," the Australian said. 

"It's not okay. I know that people don't like when I just speak out about things, be honest about things."

Sinner was cleared of any wrongdoing by the International Tennis Integrity Agency (ITIA) but the World Anti-Doping Agency has launched an appeal against it at the Court of Arbitration for Sport. 

Swiatek, meanwhile, accepted a one-month ban after testing positive for trimetazidine.

Former world number one Simona Halep, who was given a four-year ban for doping violations which was later reduced, recently questioned the "big difference" in how doping cases were treated by the ITIA after Swiarek was handed a one-month ban for her positive test.  

Kyrgios will be in action against Giovanni Mpetshi Perricard in the men's singles event of the Brisbane International while he will also partner Novak Djokovic in the doubles competition.