An estimated 648m plastic bags are used in Wales each year
The Welsh environment minister wants legislation to discourage the use of free "one-trip" plastic shopping bags.
Jane Davidson said: "They are not usually bio-degradable and represent a waste of resources."
Ms Davidson has asked officials to start work on legislation and said the "tide appears to be turning" with shoppers wanting greener alternatives.
Conservatives welcomed the move and called on the minister to "act quickly" to introduce the levy.
An assembly committee has called for a levy on the bags after rejecting a proposal for a complete ban on them.
Ms Davidson, who was on a visit to packaging firm in Newport, said officials would be undertaking the necessary work for possible regulation under the provisions of the Climate Change Act.
"Currently there is a voluntary agreement where certain retailers have agreed to reduce the number of single use carrier bags by 50% by May this year - this is a good target. "
But she said this still left half using one trip plastic bags.
Speaking later to assembly members she said she was "intending to consult on regulations to introduce a levy on single use bags in the summer".
"The exact timetable of the introduction is yet to be decided and will need to form part of the consultation."
The assembly government can introduce a levy with powers under the UK Government's Climate Change Act, which became law at the end of last year.
But it does not have the powers to decide how the funds raised would be used.
Ms Davidson said her officials were examining ways of ensuring that, by the time the levy is introduced, the funds would be passed to an independent body which would use the money for environmental projects.
Conservative environment spokesman Darren Millar said the levy was need to tackle "a huge litter problem across Wales".
"We have consistently said that whilst we welcome the piecemeal town-by-town, or shop-by-shop approach which we are seeing across Wales at the moment is not delivering change quickly enough," he said.
"Introducing this levy on plastic bags will hopefully provide us with a nationwide scheme which has the support of manufacturers, retailers, consumers and environmental groups," Mr Millar added.
Liberal Democrat Mick Bates said a levy would not only reduce the number of plastic bags used but would also "act as a catalyst to increase public awareness of litter and environmental issues generally".
"I congratulate the minister on her support for introducing a levy on plastic bags and will hold the minister to her promise to consult on the regulations in June," he said.
"The big question for the minister is how she will get the power to nominate who uses the money raised by the levy, to ensure that it is re-distributed for the benefit of the environment."
The idea to tackle the environmental issue of plastic bags in Wales started off as a petition to the assembly from Neil Evans from Carmarthenshire, who took part in a BBC Wales project to suggest a new Welsh law.
After six months of evidence gathering, the assembly's sustainability committee concluded a ban would be too difficult to police but recommended a standard charge of between 10p and 20p per bag.
The British Retail Consortium has opposed the levy proposals, arguing they are unnecessary when the industry is already cutting down on use of the bags.
Almost all of the estimated 648m plastic bags used in Wales annually are distributed free of charge.
It is believed that each bag takes between 450 and 1,000 years to degrade and collectively amount to between 0.1% and 1% of visible litter in the UK.
Sustainability Wales said the announcement was "encouraging" but it was disappointed the levy would not be introduced immediately.
A spokeswoman said the legislative process involving Westminster was "sluggish and frustrating".
The Irish Republic introduced a levy on plastic bags in 2002 which resulted in a 90% drop in the use of them across the country while China and Israel also have a charging system in place.
Bhutan and Bangladesh have completely outlawed bags with France due to bring in its own national plastic bag ban in January 2010.