Sydney: Nick Kyrgios has accused Olympic great Dawn Fraser of being a "blatant racist" after she said tennis players should "go back to where their parents came from" if they did not set a better example to Australian youth.

The former champion swimmer, after initially standing by her comments and denying they were racist, later issued an "unreserved apology for any comments... which may have caused offence to my fellow Australians including Nick and his family".

Kyrgios was the subject of a barrage of criticism back home for his on-court antics when he was beaten by Richard Gasquet in the fourth round of the Wimbledon on Monday.

The 20-year-old was accused of giving up, or "tanking", in one game, received a warning and a fine for an audible obscenity and conducted a running debate with the umpire throughout the match.

Fraser, who has been one of Australia's sporting legends since she won the 100m freestyle at three successive Olympics from 1956, was invited to comment on his behaviour on a popular morning TV show.

"It's absolutely disgusting. I am so shocked to think that he went out there to play and he tanked, he did all that tanking, that's terrible," the 77-year-old said.

"They should be setting a better example for the younger generation of this country, a great country of ours.

"If they don't like it, (they can) go back to where their fathers or their parents came from. We don't need them here in this country if they act like that." Kyrgios responded by linking to a video of Fraser's comment on his Facebook page.

"Throwing a racket, brat. Debating the rules, disrespectful... Showing emotion, arrogant." "Blatant racist, Australian legend." After denying the comment was racist, Fraser later issued a formal statement of apology.

"My intended message, which was not delivered as articulately as it could have been, was on a purely sporting level rather than meant as an attack on Nick's ethnicity.

"Nick's representing Australia and I want to see him representing Australian tennis in the best possible light."

Kyrgios, who was born and raised in Australia's capital Canberra, has Greek and Malaysian-born parents.

Ironically, Fraser was something of an anti-authoritarian figure in her heyday. A 10-year ban for various misdemeanours during the 1964 Tokyo Games, including taking a flag from outside the Japanese emperor's palace, scuppered her hopes of winning a fourth straight Olympic title in Mexico in 1968. (Reuters)