Shamil Tarpischev, president of the Russian Tennis Federation, has been forced to apologise for his slur against the Williams sisters, Serena and Venus.

The International Tennis Federation came under fire from Martina Navratilova for failing to act after Tarpischev described the US duo as "brothers".

The Womens' Tennis Association responded swiftly to Tarpischev's remarks by banning him for a year and issuing a fine of £15,500.

Navratilova, however, claimed the ITF's silence on the matter was "pretty deafening". The 59-times Grand Slam champion added: "Certainly this kind of bullying comment cannot be tolerated from anyone, but particularly from a high-up official in the tennis world."

ITF president Francesco Ricci Bitti, subsequently made it clear that derogatory comments will not be tolerated.

"Although Mr Tarpischev assured us his comment was meant as a joke, we made it clear to him what he said is inappropriate in any context," said Bitti.