Nairobi: Kenyans producing, selling or even using plastic bags will risk imprisonment of up to four years or fines of US$40,000 from Monday, as the world's toughest law aimed at reducing plastic pollution came into effect.

The East African nation joins more than 40 other countries that have banned, partly banned or taxed single use plastic bags, including China, France, Rwanda, and Italy.

Many bags drift into the ocean, strangling turtles, suffocating seabirds and filling the stomachs of dolphins and whales with waste until they die of starvation.

"If we continue like this, by 2050, we will have more plastic in the ocean than fish," said Habib El-Habr, an expert on marine litter working with the UN Environment Programme in Kenya.