BBC News -- Rwanda is cracking down on the use of plastic bags by shoppers, the environment minister has told the BBC.
Drocella Mugorewera said that anyone using plastic bags is breaking a recent law on environmental protection aimed at cleaning up cities.
She says that people must use paper bags instead. Some shoppers, however, prefer cheaper reusable plastic bags.
Some Rwandans accuse government militias of using the law to steal goods being carried in plastic bags.
One woman told the BBC's Geoffrey Mutagoma in the capital, Kigali, that local defence staff had thrown the glasses she was carrying in a plastic bag onto the ground.
Some market traders complain that products such as fish and meat cannot be carried in paper bags.
Our correspondent says paper bags are up to five times more expensive than plastic ones.
He says that despite the ban, some hawkers continue to secretly sell plastic bags, hiding them in their pockets.
The environment minister admits that it will be impossible to completely end the use of plastic bags but she believes the measure to stop traders from importing and selling them will go a long way to protecting the environment.
"In Rwanda we have not yet reached the same level of development with other some countries which use plastic bags," she said.
"They have factories that recycle used bags. Even their citizens understand that it's wrong to throw rubbish anywhere. In our case we are still teaching our citizens."
In 2004, thousands of people were encouraged to take the day off work to help pick up some of the plastic bags which littered the country.
Thousands of Rwandans have taken the day off work to pick up plastic bags as part of a government attempt to clean up the environment.
Shops have been banned from giving plastic bags to their customers and police are reportedly stopping plastic-bag users in the street.
Some supermarkets have been closed down for flouting the ban, said environment minister Drocella Mugorewera.
"We want people to use traditional baskets instead," she said.
The government has always been keen to keep Rwanda clean and correspondents say the capital, Kigali, is much cleaner than other African cities, where thin blue plastic bags can been seen in fields and on trees fluttering in the wind.
"We have a real problem with plastic and we are linking this with our efforts to protect our rivers and lakes," Ms Mugorewera told Reuters news agency.
But some shop-owners feel the government is being too heavy-handed.
"The government is being unfair to small business owners, some of us cannot afford expensive packing materials, our clients are running away," said one kiosk owner.