A 10p tax on plastic bags would bring only limited environmental benefits to Scotland, according to research.
A levy would only apply to plastic bags and not paper bags
The Scottish Executive ordered the study after a bill by Lib Dem MSP Mike Pringle proposed such a levy.
Researchers said plastic bags accounted for less than 1% of litter and would have a "minor" impact on the country's overall litter problem.
But Mr Pringle argued that such studies underestimated the impact that changing perceptions could make.
The research said that although there would be environmental gains, paper bags had a greater effect on the environment than conventional plastic carrier bags.
"If paper bags are excluded from the levy, as currently proposed, we estimate that paper bag usage will increase by 174 million bags per year to 213 million per year," said the report.
"This will have associated environmental implications in terms of increased energy use, transport costs, storage space and waste disposal."
The levy would reduce the number of plastic bags used each year by 697 million.
There would be increased demand for long-lasting bags, bin liners and paper bags, resulting in an estimated fall of 3,484 tonnes of polythene used in Scotland.
But it said there would be a rise of 8,893 tonnes of paper.
Applying the levy to paper bags would result in a reduction of 3,214 tonnes of polythene a year, and an annual decrease of 1,779 tonnes of paper.
The Lib Dem MSP welcomed the study but added: "Whilst studies such as this are useful, they can often underestimate how big an impact changing behaviour and perceptions can make.
"The levy in Ireland has been phenomenally successful in reducing unnecessary use of plastic bags. I believe my bill will help change perceptions towards our use of resources in Scotland as well."
However, store owners said the proposals would be an "administrative nightmare" which would actually have the effect of increasing waste.
The Carrier Bag Consortium said the report had found that it could result in 700 jobs being lost.
CBC chairman Barry Turner said: "Emotive misinformation and political spin has described plastic carrier bags as a menace.
"But in the face of that, the experts commissioned by the Scottish Executive have reached many robust conclusions.
"They effectively dismantle the environmental myths surrounding the effects a plastic bag tax would have on Scotland and its people."
The Scottish Retail Consortium (SRC) argued that the official findings offered "very little justification" for introducing a fee under the Plastic Bags (Scotland) Bill, which could become law some time in 2007.
Spokeswoman Fiona Moriarty said: "We see this debate becoming extremely emotive to the point where delivering any true environmental, social or economic benefit is becoming less of a priority.
"The scheme is flawed and we are not convinced that it delivers genuine environmental benefits."
She added: "The introduction of a levy on carriers will unfairly penalise the innovative steps being made towards the manufacture of bags from recycled plastics or using biodegradable plastics.
B&Q started charging for its plastic bags in its Scottish stores last year
"A tax should encourage markets for recycled plastic carriers instead of penalising alternatives."
But Mr Pringle said he was sceptical about the predictions the report made about job losses.
His proposal has the backing of Friends of the Earth Scotland, which said it would save resources and benefit the country's environment.
Head of research Dr Dan Barlow said the Scottish Executive should either bring forward its own legislation or support Mr Pringle's bill.
Green MSP Shiona Baird said Scotland needed to do much more to tackle its record on waste.
She also said environmental benefits should be above any "short-lived inconvenience" to retailers.
"The retail lobbyists are trying to deny the success of the Irish scheme," she said.
"They are scare-mongering regarding a possible rise in the use of paper bags.
"Scotland desperately needs to reduce the amount of overall resources used and waste produced."
An executive spokeswoman said: "We will see what evidence is presented and what progress we make with the retailers on our proposed code of practice on providing plastic bags.
"Our message to consumers is very straightforward: re-use bags wherever possible."