DAR ES SALAAM, Tanzania — Kenya will now punish with up to four years in jail anyone making, selling or importing plastic bags, putting in place one of the world’s toughest bans on the ubiquitous item that is blamed for clogging oceans and killing marine life.

The new rule, announced in March and put into effect on Monday, also means that garbage bags will be taken off supermarket shelves and visitors entering Kenya will be required to leave their duty-free shopping bags at the airport.

Kenya joins more than 40 other countries including China, the Netherlands and France that have introduced taxes on bags or limited or prohibited their use.

In Rwanda, plastic bags are illegal, and visitors are searched at the airport. Britain introduced a 5 pence charge at stores in 2015, leading to a plunge of more than 80 percent in the use of plastic bags. There are no nationwide restrictions on the use of plastic bags in the United States, though states like California and Hawaii ban nonbiodegradable bags.