It was announced that while Kumar was stepping down as chairman, he would remain a member of the ARU board.
Kumar appears to have sacrificed himself in a bid to mend relations with the New Zealand Rugby Union, according to Australia's Daily Telegraph, following the ARU's decision to support Japan's failed bid to stage the 2011 World Cup.
But the decision comes as a surprise, as the successful businessman has been one of the most influential powerbrokers in the game.
The ARU takes over the secretariat of SANZAR [the organisation representing the unions of Australia, South Africa and New Zealand] and Kumar is said to have stood down as chairman to ensure a smooth transition.
While it was an ARU board decision to support Japan's bid, it was understood that the New Zealanders blamed him for Australia's decision not to support their bid.
Relations between the nations were said to have sunk to their lowest ebb since Australia got the sole rights for the 2003 World Cup when New Zealand could not deliver sponsorship-clean stadiums.
