Shoppers will have to pay for plastic shopping bags when a proposed amendment to the 1992 Environment Act is passed, deputy director-general of the Department of Environmental Quality Promotion Sermyos Somman said.
Mr Sermyos did not reveal when people would have to pay for their bags but he elaborated on the push to educate people about the issue.
He was speaking while visiting department stores which have joined a campaign to reduce the use of bags. Shoppers have welcomed the campaign, he said.
From Aug 15, the government has been encouraging shoppers to use as few plastic bags as possible.
The campaign involves asking shoppers to avoid using the bags on the 15th of each month. Several department stores and convenience store chains have joined hands in providing consumers with incentives to avoid taking plastic shopping bags.
Shoppers who say "no" to taking plastic bags at 15 supermarket chains and convenience stores will receive rewards.
Regular shoppers with membership cards at some supermarkets, including those operated by Central Group and The Mall Group, will receive extra reward points if they bring their own shopping bags.
Mr Sermyos revealed that on Aug 15 alone, 1.8 million fewer plastic bags were used by shoppers.
The department and its allied business operators were considering expanding the campaign to also cover the 30th of every month, he said.
The campaign aims to reduce plastic bag waste by 10% in the scheme's first three months and start a trend of shopping with tote bags. Mr Sermyos said waste management has been put on the national agenda.
The Natural Resources and Environment Ministry said plastic and styrofoam waste creates 2.7 million tonnes of rubbish a year.