Rugby Australia chief Raelene Castle felt compelled to write a letter of apology over the behaviour of the Wallabies squad at the World Cup, according to media reports.

Tournament organisers were said to have been unhappy with a number of the Australian contingent in Japan, including former coach Michael Cheika, according to The Sydney Morning Herald.

The paper quotes an unnamed source, who reportedly saw Castle’s letter, in which she bids to made amends for Cheika’s criticism of World Rugby and referees, and presenting a general “us against them” attitude during the tournament.

In particular, Cheika criticised the decision to slap Wallabies winger Reece Hodge with a three-week suspension for a dangerous tackle on Fiji’s Peceli Yato, which left World Rugby bosses unimpressed.

Cheika revealed after the tournament that he would not seek an extension to the five-year spell he served after the Wallabies were beaten 40-16 by England in the quarter-finals.

The Herald report also said World Rugby had opted not to comment when contacted for a reaction.