On the eve of the IRB Junior World Championship 2010 semi finals, International Rugby Board Referee Manager Paddy O'Brien has labelled the standard of officiating at the tournament as "up with the best" and a vital part of a referee's development.

"This tournament is hugely important for the development of a referee," explained O'Brien, who has seen Andrew Small, Keith Brown, Chris Pollock and Jerome Garces graduate from last year's Junior World Championship to the International Panel in 2010.

"All of them have had experience, whether it be at European or Super 14 level, but this is the opportunity for the IRB selectors to get a good look at them on and off the field and to give them work ons to go home with.

"History shows that the future IRB panel referees come from age grade tournaments and clearly some of the referees here are international referees of the future."

O'Brien was speaking after announcing the match official appointments for the penultimate round of matches in Argentina, which will see England, Australia, South Africa and two-time defending champions New Zealand compete for a place in the final on Monday.

New Zealand referee Garratt Williamson will take charge of the first semi finals at the Estadio El Coloso del Parque between England and Australia, which kicks off at 14:10 local time on Thursday and will be streamed live on IRB.com.

John Lacey of Ireland will referee the second semi final - kicking off at 16:30 local time and again streamed live on the IRB website - between New Zealand and South Africa with Frenchman Pascal Gauzere and Argentina's Federico Anselmi acting as assistant referees for both matches.

Tough call for semi final appointments

"In the selectors' view there are four stand outs at this tournament and the other four have performed well so in the end we had to go with those we believe have been the most consistent [for the semi finals]," admitted O'Brien.

"We do not want the semi final referees to change in any way their approach to the matches. They have been selected on the form they have shown to date and apart from modifying areas identified by the selection panel as weaknesses we ask them to referee the same as they have in the pool matches."

The Championship also continues in Santa Fe and Paraná with the first hosting the two play-offs for fifth to eighth place and the latter the ninth to 12th places with no side wanting to finish bottom and be relegated to next year's IRB Junior World Rugby Trophy.

Scotland referee Peter Allan has been handed the whistle for the opening match at the Estadio CA Colon in Santa Fe between Wales and hosts Argentina at 14:00 local time. Nathan Pearce of Australia will then referee the encounter between France and Fiji at the same venue at 16:15 with Uruguayans Joaquin Montes and Luis Caviglia the assistant referees.

The Club Atlético Estudiantes in Paraná will host the matches involving Ireland, Samoa, Scotland and Tonga. Jaco Peyper of South Africa will referee the match between Ireland and Samoa, two sides who did not win a match in the Pool stages.

Francisco Pastrana of Argentina then takes charge of the encounter between Scotland and Tonga at 15:00 local time. The two sides only met on Sunday, when the Scots ran out 27-3 winners. Argentineans Martin Rodriguez and Emilio Traverso will run the line in both matches.