Wellington, March 11 NZPA - Southern hemisphere rugby officials are on the lookout for a chief executive to develop the annual Super and Tri-Nations competitions.

South African, Australia, New Zealand Rugby (Sanzar) has until now rotated the responsibility of running the Super 14 and Tri-Nations competitions between each of the three unions.

"The Sanzar joint venture has been incredibly successful through the co-operation of the three unions which have rotated the secretariat responsibilities up until this year," New Zealand Rugby Union chief executive Steve Tew said in a statement.

"With the expansion of the competitions from 2011, it is timely to move to an independent, permanent executive that can focus exclusively on driving Super rugby and the Tri-Nations competitions."

A 15th Super rugby team are to begin playing in Melbourne next year, with the competition being altered to a conference-based tournament with five teams based in each country.

The Tri-Nations is also expected to expand in 2012 after Sanzar invited Argentina to join the championship.