Hayden, who made the comment on Tuesday during a Brisbane Radio interview, was tonight hauled before a Cricket Australia code of conduct hearing after being charged with making a "detrimental public comment" about Singh.
The hearing was held at Cricket Australia's Jolimont headquarters in Melbourne from 8 p.m. local time. It was presided over by code of conduct commissioner Ron Beazley.
Unlike verbal barbs directed on the field - an ICC portfolio - Hayden's decision to air his views in a radio interview, which was picked up and run with by national newspapers this morning, left him open to sanction by Cricket Australia.
The charge fell under Rule 9 of the CA Code of Behaviour, which prohibits 'detrimental public comment'.
"Rule guidelines prohibit public denigration of other players against whom they have or will play," CA public affairs manager Peter Young said.
Hayden's hearing occurred at least partly because of Indian reaction to his comment.
The Board of Control for Cricket in India (BCCI) expressed its displeasure over Hayden's remarks and had lodged a protest with CA.
"We condemn such comments by the Australian players," BCCI's chief administrative officer Ratnakar Shetty told a foreign news agency.
"Our secretary has already communicated our feelings to Cricket Australia. We've advised our players to show restraint, but despite that if such comments are being made it is really unfair. CA have said they will look into this and let us hope there is some communication on this," added Shetty.
Indian team manager Bimal Soni said the players did not want to publicly respond to Hayden's comments, but added that the team's stance on Australians unwarranted sledging had been proved beyond doubt.
Earlier, Harbhajan Singh reacted by saying that Hayden's comment on him was indication of Australia slipping from its championship pedestal, a position it has claimed since 1995.