Hundreds of Wales versus Ireland Six Nations tickets will be invalid after the Welsh Rugby Union (WRU) took a reseller to court.
The WRU obtained a High Court injunction against an operation which was reselling tickets and hospitality for the 2017 RBS Six Nations matches at the Principality Stadium in Cardiff.
Evental Ltd was the subject of a ruling by the High Court of Justice at a hearing in London on March 1, a statement from the WRU confirmed.
The ruling prevents Evental Ltd, its director or anyone acting on its instruction from breaching the terms and conditions of sale of WRU tickets by selling them on for profit.
As part of the court proceedings, Evental Ltd was required to reveal both where its tickets had been sourced and to whom they had been sold.
As a result, the WRU said that it is aware of around 200 tickets for Friday night's Wales versus Ireland match in Cardiff which have been sold on to other parties in breach of the WRU's ticketing terms and conditions. The fixture at Principality Stadium has sold out.
The union warned that it is now taking steps to cancel these tickets.
Its statement said: "It is against the WRU's ticket terms and conditions to resell tickets above face value anywhere other than via its officially licenced secondary market website, Seatwave - which is itself subject to detailed regulation to ensure profits made stay in Welsh Rugby and to protect consumers.
"The only other official ticket sources are the WRU's sole off-site hospitality operator Events International, WRU onsite hospitality, WRU member clubs and official travel partner Gullivers Sports Travel."
Supporters who have bought tickets from Evental Ltd, or any other unofficial source, are encouraged to get in touch with the WRU via email@example.com immediately in order to check validity.
The WRU added: "These tickets do not carry a guarantee of entry into Principality Stadium." The WRU was awarded £21,338 (€24,000) damages.