A blanket ban on the import, manufacture or sale of disposable plastic products and shopping bags, after a garbage dump collapse killed 32.
Sri Lanka banned plastic bags and other disposable products on Friday after the collapse of the island's biggest dump led to a rubbish disposal crisis.
Rotting garbage piled up in many parts of the capital after the giant rubbish tip collapsed in April, crushing dozens of homes and killing 32 people.
Many blamed the haphazard use of plastic, which was also cited in flash flooding in the capital after storm water drains became clogged.
In response, President Maithripala Sirisena banned the sale of plastic bags, cups and plates, as well as the burning of refuse containing plastic.
"Any person who fails to comply with the regulations ... shall be liable to an offence and punishable under the National Environmental Act," the president said.
Offenders could be fined $66 (10,000 rupees) and jailed for up to two years.