Competition like football: Harper

Big business should be able to play competitively, like in a game of football, but be penalised if their actions harm the game.

That's how the man behind the nation's biggest review of competition laws in two decades is explaining a recommendation to apply an "effects test" to check the misuse of market power by big businesses.

Ian Harper says like a football game, big business will always argue the cut and thrust of increasing competition involves harm to competitors.

"That ought not to be a problem in itself but if their actions harm the game, that is harm the competitive process, that's a different story," he told ABC radio on Wednesday.

Independent senator Nick Xenophon says the insertion of an effects test is a "complete mishmash" and will entrench the dominance of big players like Coles and Woolworths.

"Essentially it will render it completely ineffective," he said.

Small Business Minister Bruce Billson says existing provisions in the law don't have the teeth to curb harmful behaviour.

It was natural for uncertainty to surround the potential new clause given it was designed to bring about change to a familiar system, he said.

The whole point of competition laws were to place "bumper rails" on big business and economically damaging conduct.

"It's designed to encourage people to be more circumspect, particularly where they've got a very dominant market position," Mr Billson told ABC radio.