(REUTERS) - Twenty-three-time Grand Slam champion Serena Williams said she would have faced far harsher punishment had she engaged in similar behaviour to German Alexander Zverev, who was thrown out of a tournament last month for unsportsmanlike conduct.

The world No. 3 was kicked out of the ATP 500 event in Acapulco, Mexico after he smashed his racket repeatedly against the umpire's chair after a doubles defeat.

Zverev was later fined US$40,000 (S$54,400) for the incident, in which he came perilously close to hitting umpire Alessandro Germani.

"There is absolutely a double standard," former world No. 1 Williams told CNN reporter Christiane Amanpour.

"I would probably be in jail if I did that - like, literally, no joke.

"I was actually on probation once," she added, but declined with a chuckle to discuss further when Amanpour inquired about the incident.

In 2009, the Grand Slam committee placed Williams on probation for two years and fined her US$175,000 for a "major offence of aggravated behaviour" during her semi-final against eventual champion Kim Clijsters at the US Open.

"You see that (double standard) when you see other things happening on the Tour, like, 'wait - if I had done that? Hmm,'" said Williams.

"But it's okay. At the end of the day, I am who I am and I love who I am."