A UK-wide ban on the manufacture of cosmetics and care products containing tiny pieces of plastic known as "microbeads" has come into force.
The move is aimed at protecting the marine environment from one source of plastic pollution, as microbeads are washed down the drain and can enter the seas and be swallowed by fish and crustaceans with potentially harmful effects.
Manufacturers of cosmetics and personal care products will no longer be able to add the tiny plastic pieces to rinse-off toiletries such as face scrubs, toothpastes and shower gels.
It will be followed by a ban on the sale of products containing microbeads later in the year, the Government said.
Environment minister Therese Coffey said: "The world's seas and oceans are some of our most valuable natural assets and I am determined we act now to tackle the plastic that devastates our precious marine life.
"Microbeads are entirely unnecessary when there are so many natural alternatives available, and I am delighted that from today cosmetics manufacturers will no longer be able to add this harmful plastic to their rinse-off products.
"Now we have reached this important milestone, we will explore how we can build on our world-leading ban and tackle other forms of plastic waste."
Dr Sue Kinsey, senior pollution officer at the Marine Conservation Society, welcomed the "robust" ban, which she said was the strongest and most comprehensive in the world.
"We believe that this signals a real commitment on the part of this Government to clean up our seas and beaches and hope this is a first step on this road before we see further actions to combat plastic waste."
Labour's Mary Creagh, chairwoman of the parliamentary Environmental Audit Committee, which had called for the ban, said it was a step in the right direction, but more needed to be done.
"Our seas are choked with massive quantities of polluting microplastics, which absorb chemicals, are eaten by wildlife and enter the food chain.
"Microbeads in cosmetics are an avoidable part of the problem, which is why we called for a ban."
And she said: "Since we called for a ban, my committee has also recommended a deposit return scheme for plastic bottles, a latte levy for plastic-lined coffee cups and reforms to make producers responsible for their packaging.
"We look forward to hearing the Government's response."