Starbucks is to test a 5p charge for paper cups across all of its 950 stores in Britain following a three-month trial.
The charge will see all stores add 5p on to the cost of any drink bought in a paper cup from July 26 to encourage customers to bring in reusable cups in return for a 25p discount.
The extended test comes after the trial showed a 126% increase in the use of reusable cups in participating stores, measured by the number of customers redeeming the 25p discount.
Starbucks has offered a £1 reusable cup to customers since 2014.
A report on the trial by environmental charity Hubbub shows that the percentage of customers bringing in their own cup or tumbler increased in the stores involved from 2.2% beforehand to 5.8%.
Some 8% of all hot drinks served in the mornings were in reusable mugs or tumblers, Hubbub found.
Starbucks said it was sharing the findings of its trial with the wider industry and was continuing to look at alternatives to single-use paper cups, such as its policy of serving all drinks to be consumed in stores in ceramic cups.
On Monday he coffee giant said it would eliminate plastic drinking straws, and introduce lids designed not to need straws, within two years to combat the stress they put on marine life and the environment as a whole.
Starbucks Europe president Martin Brok said: “We saw encouraging results from the first three months of this trial with Hubbub, and what stood out to us was the positive response we had from our partners and customers who continue to push us to innovate and find ways to reduce waste.
“Extending this to all our stores across Britain is an exciting step and we’re hoping this charge will remind customers to rethink their use of single-use plastic as it has with plastic bags.”
Hubbub founder Trewin Restorick said: “Single-use plastics is an issue that has become more significant in people’s minds than ever before. The trial proved this, showing that customers have an increased awareness of the need to reduce waste from single-use cups.
“A 5p charge is an effective way to prompt this change.”
A number of chains serving takeaway hot drinks have recently announced moves to curb disposable cup waste, including Costa Coffee which pledged to recycle as many as it hands out by 2020, and Waitrose which plans to phase them out by the autumn.
Earlier this year, Environment Secretary Michael Gove said the Government would consider a 25p “latte levy” on disposable coffee cups, following the success of the 5p charge levied on plastic bags.
Government ministers later rejected the proposal and instead said it would rely on voluntary action from retailers.