The position was originally offered to Mike Ruddock but the Wales head coach has decided he needs to be with the under-21 side at their World Cup in Argentina.

Johnson, an Australian, was recruited by former Wales coach Steve Hansen and played an integral role in the development of this year's Grand Slam-winning side.

Lions head coach Sir Clive Woodward said: ''It's great news that Scott Johnson is going to be in New Zealand with a watching brief for the WRU.

''I saw him close up when I was with Wales during the Six Nations. He is a terrific coach and he is also someone who understands the game in the southern hemisphere.''

Johnson is looking forward to sharing opinions with Woodward's vast coaching staff that might help Wales in the defence of their RBS Six Nations crown.

''It will be great to witness 'our boys' working within a different environment other than our own,'' said Johnson.

''To see them grow and develop under a different set of people will be of great benefit to myself and the Welsh players and management.

''The tour is the culmination of all that is good about rugby in the home nations and being able to share opinions and points of view with people from different approaches and backgrounds can only be of huge benefit, not only to myself but ultimately it will also help the development of Welsh rugby.

''If there's anything I can give to the tour management team by way of knowledge of southern hemisphere rugby and of the New Zealand coaches, I will, of course be forthcoming.''

As well as monitoring the fortunes of the Wales Under-21's - who also won the Grand Slam during the season - Ruddock is also committed to completing the final module in his Level Four coaching course.

Ruddock said: ''We would like to thank Clive Woodward and the Lions for the fantastic opportunity of being able to take up an observational role with the Lions in New Zealand.

''We certainly would not want to turn down that offer and while I cannot make it, there is no better man that Scott to represent Welsh rugby in that way.

''It is important for me and the future of the Wales team that I travel to Argentina to see the under-21 players who could be vying for places in the national side by the time we get to the next World Cup in 2007.

''We have a massive season ahead with four autumn internationals, the defence of our RBS Six Nations title and a tour to Argentina.

''It is important to me and for the coaching structure in place in Wales that I complete my Level Four coaching course and my final module - on management - is still outstanding. I feel if I don't finish it this summer, I never will!''