The English RFU has launched an investigation into allegations of homophobic abuse of referee Nigel Owens at Twickenham last Saturday.
It is claimed that Owens, who is gay, had been the subject of discriminatory taunts by supporters during England's 24-21 defeat by New Zealand in the opening QBE International.
"We take any allegations of any abuse very seriously and are investigating this matter," an RFU spokesperson said.
The matter was first brought to light when a spectator witnessed the abuse from a group of men he estimated to be their mid-30s and subsequently wrote a letter to a national newspaper outlining what he had heard.
"I could not believe that a bunch of men half my age watching a rugby match in the 21st century could be capable of hurling such nasty, foul-mouthed, racist, homophobic abuse at an openly gay match official," read the letter published in The Guardian.
While the RFU stresses that allegations of abuse of any type at Twickenham are extremely rare, it states that it is taking the matter "very seriously".
"The RFU condemns all forms of discrimination and aims to ensure that all people, irrespective of their age, gender, ability, race, religion, ethnic origin, creed, colour, nationality, social status or sexual orientation, have a genuine and equal opportunity to enjoy rugby union in whatever form, on or off the pitch, at all levels and in all roles," an RFU spokesperson said.
Owens, considered to be among the sport's leading officials, has called for bans to be issued if the allegations are proven.
"If someone has gone to the trouble to send a letter to the paper and say that this was disgusting and the behaviour was totally out of order, then I would think what they shouted was pretty bad and if that is the case then these people should be banned from the game," Owens told The Daily Telegraph.
"They need to be told that some behaviour is not acceptable, that crossing the line of what is humour and banter is a fine line but if you cross it then you have to put up with the consequences."