Roger Lewis, WRU Group chief executive, said: "Saturday's event is going to be an outstanding occasion and I'm delighted we have found a way to release some extra tickets to the general public."
The Millennium Stadium is well versed in sell-out crowds and squeezing in extra seats is usually reserved for events such as the FA Cup Final, but this weekend is arguably the biggest fixture in the Welsh sporting calendar so bosses have left no stone unturned to ensure the maximum amount of fans get access to the game.
"Even before Gareth Jenkins announces his team for Saturday, the Welsh public are backing their heroes to the hilt," added Paul Sergeant, Millennium Stadium chief executive.
"We have been able to reward the fantastic Wales supporters by getting these extra seats in, as we do for an event such as the FA Cup Final when the demand is so high. We have fulfilled all club orders, debentures and disabled patrons and these new temporary seats will occupy all available space."