Coca-Cola increased its production of throwaway plastic bottles last year by well over a billion, according to analysis by Greenpeace.

The world’s biggest soft drinks company does not disclose how much plastic packaging it puts into the market. But analysis by the campaign group Greenpeace reveals what they say is an increase in production of single-use PET bottles from 2015-2016.

The increase puts Coke’s production at more than 110bn bottles each year, according to Greenpeace.

Coca-Cola has confirmed that single-use plastic bottles made up 59% of its global packaging in 2016 compared to 58% in the 12 months before.

The scale of production contributes to a plastic mountain which is growing vastly year on year. Figures obtained by the Guardian reveal that by 2021 the number of plastic drinks bottles produced globally will reach more than half a trillion.

But only a tiny fraction of these bottles are recycled. Fewer than half of the bottles bought in 2016 were collected for recycling and just 7% of those collected were turned into new bottles. Instead, most plastic bottles produced end up in landfill or in the ocean.

Between 5m and 13m tonnes of plastic leaks into the world’s oceans each year to be ingested by sea birds, fish and other organisms, and by 2050 the ocean will contain more plastic by weight than fish, according to research by the Ellen MacArthur Foundation.

Louise Edge, oceans campaigner for Greenpeace, said: “Coca-Cola talks the talk on sustainability but the astonishing rate at which it is pumping out single-use plastic bottles is still growing.

“We have calculated it produced over 110bn throwaway plastic bottles every year – an astounding 3,400 a second – while refusing to take responsibility for its role in the plastic pollution crisis facing our oceans.

“We would love Coke to provide detailed breakdowns of what it produces – so we would welcome any clarifications they have to offer on our estimates.”

Amid growing concern about marine pollution and increasing evidence that plastic is finding its way into the food chain of fish and humans, Coca-Cola European Partners announced it had changed its mind about plastic bottle deposit schemes.

The company has expressed support for a deposit scheme and told Westminster MPs a new approach was needed to improve the stalled recycling rates in the UK of 57% for PET bottles, and is calling for collaborative efforts from government and industry to improve recycling rates.

Coca-Cola, which operates in more than 200 countries, has said disclosing the volume of plastic packaging it puts on the market annually is “commercially sensitive”.

In July Coca-Cola European Partners announced it would increase the amount of recycled plastic in its bottles to 50% by 2020.

But plastic drinking bottles could be made out of 100% recycled plastic, known as RPet – and campaigners are pressing big drinks companies to radically increase the amount of recycled plastic in their bottles.

A spokesperson from Coca-Cola Great Britain said: “Our global PET bottle usage number for 2016 is 59%, an increase of 1% from 58% in 2015. We continue to review and adjust our packaging strategy as part of our overall business plan.

“In the UK, all of our bottles and cans are 100% recyclable and have been since 2012. Our plastic bottles contain 25% recycled material and we have recently pledged to double this amount to 50% by 2020.”