Opposition Leader Tony Abbott may not support plain-packaged cigarettes as the tobacco industry threatens to slash the cost of cigarettes if the Gillard government pushes ahead with the anti-smoking legislation.

Mr Abbott, who is yet to back the government's proposal, says he is happy to support any policy that has been proven to curb smoking rates.

"But my anxiety with this [plain packaging proposal] is that it may end up being counterproductive in practice," he told reporters today.

Health campaigners and Health Minister Nicola Roxon have branded the tobacco industry's threat to cut the cost of cigarettes if plain packaging is introduced as a stunt.

Ms Roxon said she expected the fight from the tobacco industry, but not from Mr Abbott.