The tobacco industry is threatening to cut the price of cigarettes if it is forced to remove branding from packets.

British American Tobacco Australia (BATA) is making the threat as part of its campaign against the Federal Government's plain packaging plans.

But Health Minister Nicola Roxon says the price threat is a sign of how desperate the industry is to fight the changes.

BATA spokesman Scott McIntyre says the industry will unveil a series of radio, print and billboard ads today in its ongoing fight against the plain packaging laws.

"BATA will today launch a national media campaign which questions the Federal Government's proposed plain packaging experiment, while also releasing a series of confidential government documents which support the company's view," he said.

"Many of these confidential documents are obtained under Freedom of Information laws and show the Government has no credible proof that plain packaging will reduce smoking rates and that they are prepared to spend millions of dollars of taxpayers' money on legal fees."

Mr McIntyre says if plain packaging laws do go ahead, the industry will have no choice but to lower prices to stay competitive.

"Also, we've seen in the last three years a boom in illegal tobacco; it's grown 150 per cent in this country," he said.

"If you make all packets look the same and you take away the branding and trademarks, then counterfeiters in China and Asia are rubbing their hands together in glee at the thought of being able to mass produce this stuff and bring it in.

"And it's only about 30 per cent of cost price of the legal pack. So you're seeing legal cigarettes, illegal cigarettes dropping in price which, unfortunately, is likely to lead to an increase in smoking rates, which goes right against what the Government's trying to do."

But Ms Roxon says the tobacco industry will say anything to protect its branding.

"We're in this extraordinary position where they're fighting against measures the Government's taking because they think it will affect their profits," she said.

"Today they are so desperate that they're talking about slashing their own profits in order to hook people onto their products, which they can put the price up for later.

"This doesn't make sense unless you can see through their plans."

Greens Senator Rachel Siewert has called the price war threat a desperate move that would put profit ahead of people's health.

She has renewed her call for a minimum price on tobacco products.

"We believe it is more appropriate that the Government puts in place a floor price on cigarettes to stop this ridiculous race to the bottom, where the tobacco industry will encourage discounting on cigarettes," she said.

"Clearly the price of cigarettes plays a very important role in stopping people smoking."

'Extremely litigious'

Ms Roxon described the tobacco industry as already having a public record of being "extremely litigious".

"But we simply won't let threats of litigation stop us from taking the course of action which we believe will help save lives," she said.

Mr McIntyre says there is no evidence to support the claim that smoking rates will drop as a result of plain packaging.

"The Government is putting together this legislation so they're the one that needs to supply the evidence that the legislation ... is based on evidence and it is going to work," he said.

But Ms Roxon will not be drawn.

"We're confident this measure will have an impact. We won't be silly in making assertions about how many people it will affect," she said.

"But we are very confident and we are more confident every day when big tobacco yells and screams and scratches, that this measure will have a big impact and that that's why they're fighting so hard to stop it."

Ms Roxon says she is determined to bring the plain packaging legislation into Parliament during the winter sitting.