World Rugby has opened an investigation into the alleged racist slur directed at England flanker Tom Curry by South Africa hooker Mbongeni Mbonambi in Saturday's World Cup semi-final. The global governing body said on Monday it was formally looking into the claim, which -- if proven -- threatens Mbonambi's participation in the final against New Zealand on Saturday. Curry claimed to referee Ben O'Keeffe in the second quarter of the Stade de France clash - which the Springboks won 16-15 - that he had been called a "white c***" by Mbonambi. "World Rugby takes all allegations of discriminatory behaviour extremely seriously," a statement read. "We can confirm that we are formally reviewing the allegation made by England's Tom Curry in relation to the use of discriminatory language during the England versus South Africa Rugby World Cup 2023 semi-final on Saturday. "World Rugby will not be making further comment until the conclusion of the process." South Africa said on Sunday they are "aware of the allegation, which we take very seriously," and are "reviewing the available evidence." "We will engage with Bongi if anything is found to substantiate the claim," SA Rugby said. When asked after the match if Mbonambi had said something he should not have done, Curry said: "Yeah." He declined to reveal the content of the remark. Mbonambi took over as captain once Siya Kolisi was replaced early in the second half against England. With AP. Australian Associated Press