Bongi Mbonambi in the clear after World Rugby closes case against him

Curry claimed to referee Ben O'Keeffe in the second quarter of England's World Cup semi-final defeat by South Africa on Saturday that he had been called a "white c***" by hooker Mbonambi.

England's Rugby Football Union (RFU) also told the inquiry that Curry "had also been the victim of the same abuse, from the same player" when the rivals clashed at Twickenham last November.

But World Rugby announced it was unable to find evidence of either incident and closed the case.

"Any allegation of discrimination is taken extremely seriously by World Rugby, warranting a thorough investigation," a statement read.

"Having considered all the available evidence, including match footage, audio and evidence from both teams, the governing body has determined that there is insufficient evidence at this time to proceed with charges.

"Therefore, the matter is deemed closed unless additional evidence comes to light.

"World Rugby is also concerned by the social media abuse that both players have been subjected to this week," it added.

"There is no place in rugby or society for discrimination, abuse or hate speech, and World Rugby urges fans to embrace the sport's values of respect, integrity and solidarity."

Meanwhile, SA Rugby acknowledged World Rugby's decision in a short statement.

"SA Rugby has noted World Rugby's announcement concerning their investigation into an incident arising from the Rugby World Cup semi-final and welcomes the decision that no further action will be taken," it said.

"Any form of racism is abhorrent to SA Rugby and the Springbok team whose purpose is to do everything in its power to assist in uniting our diverse and multicultural nation.

"Bongi Mbonambi is an experienced, respected and decorated Test player and, needless to say, denied the allegations from the outset. SA Rugby has absolute faith in the honesty and integrity of Bongi.

"The team's focus remains, as it has throughout the week, on Saturday's match against New Zealand."

The RFU, meanwhile, said it was 'deeply disappointed' by the decision.

"The RFU fully supports Tom Curry in raising the racially abusive behaviour he experienced. The RFU is deeply disappointed by the decision taken by World Rugby," a statement read.

"The decision not to put the evidence before an independent disciplinary panel has denied the disciplinary process the opportunity to hear Tom Curry's voice and to independently assess his account of these serious events, together with the other available evidence."

Mbonambi is set to start the World Cup final after being picked at hooker in South Africa's squad.