Roger Lewis has described the possibility of a successful 2015 World Cup bid by England as "great news" for Wales.
The Rugby Football Union has confirmed it will make a government-backed pitch for the tournament, joining three other contenders - South Africa, Italy and Japan.
The deadline for bids is this Friday, with presentations being made to the International Rugby Board Council in Dublin next Wednesday, followed by a decision during late July.
While the RFU are going it alone as potential hosts, Wales’ Millennium Stadium is among several high-profile venues that would be used in 2015, alongside the likes of Twickenham, Wembley and Old Trafford.
“I am delighted the Rugby Football Union has now confirmed their bid and declared that if they are successful matches will be played here in Wales,” said Welsh Rugby Union chief executive Lewis.
“I have been involved in detailed discussions with senior representatives of the RFU, and the outcome will be great news for the rugby public of Wales if the bid succeeds.
“I know the RFU have worked hard on their proposal, and I can promise them that everyone involved in rugby in Wales would work tirelessly to ensure the competition is a massive success.
“It is a tribute to the status of the Millennium Stadium that its significance as a British sporting arena has been recognised by our involvement in this bid.”