"We've identified the person - other spectators were kind enough to let us know who he was," Gallacher said. "All I want to say to this person face-to-face when I see him is that he's not welcome here."
The man, wearing a Scarlets shirt, threw the ball away from Lomu and verbally abused him during Monday's match at Stradey Park. Lomu brushed off the incident, however the Scarlets chief executive felt it appropriate to write to Lomu to apologise for the unsavoury behaviour of the fan. The region will also review stewarding arrangements in that part of Stradey.
Blues Chief Executive Robert Norster welcomed the tough stance taken by their Welsh regional rivals.
"The safety of players, officials and spectators is of paramount importance to us and we are encouraged to hear that Llanelli Scarlets also share this view," Norster said. "We fully support their actions in trying to identify and ban the person responsible for the incident."