The man who promoted Whitney Houston's last Australian tour has defended her against the heavy criticism of her performances, describing her as "one of the greatest singers ever".

Houston, who died on Saturday in Los Angeles, came to Australia in 2010 as part of a world tour designed to relaunch her career.

But fans demanded their money back at many of her concerts claiming her once immaculate voice was below par.

Promoter Andrew McManus agreed the tour had got off to a bad start, but claimed she was the victim of a media conspiracy.

"The media was very cruel and unfair to her," McManus said on ABC radio in Melbourne.

"The media had made a decision they were going to fry her before she got on stage."

McManus agreed Houston hadn't properly prepared for her Australian performances and had "run out of puff" after the third song of her first concert.

But she had improved as the tour progressed, he said.