Soft drinks makers admit more needs to be done to stop people discarding single-use plastic bottles.
Their UK trade body says it will work with government to reduce the number of bottles ending in the sea.
It follows research from Greenpeace suggesting the top six global firms sell plastic bottles weighing more than two million tonnes a year.
The biggest brand Coca-Cola is under fire for refusing to disclose how much plastic it produces.
A study estimated that more than five trillion plastic pieces weighing more than 250,000 tonnes were afloat at sea, and a recent paper showed that even marine organisms 10km deep had ingested plastic fragments.