The cocoa industry is failing to meet a highly publicised pledge to stop deforestation in West Africa and eliminate tainted beans from supply chains, environmental campaigners say.

Big chocolate companies and the governments of Ghana and the Ivory Coast continue to be responsible for the deforestation of tens of thousands of hectares of land over the past year in former rainforest-covered nations, despite their solemn promises to end the practice last November, the campaigning organisation Mighty Earth said.

Last year the Guardian investigated how the chocolate industry was driving deforestation on a devastating scale in Ivory Coast and Ghana, the world’s two biggest cocoa producers, including in supposedly protected “classified” forests and national parks.

Cocoa is a mainstay of the Ivorian and Ghanaian economies but their rainforests have been devastated by it. With more chocolate being devoured each year – the average Briton ate 8.4kg of it in 2017 – the few remaining forests are being cut down to meet demand.

Soon after the publication of the Guardian investigation and a study by Mighty Earth, the two west African governments made plans to stop all new deforestation and replant degraded forests.

Then, at the UN’s conference on climate change in Bonn, the cocoa and chocolate companies responsible for the purchase of 80% of west Africa’s cocoa promised to end forest destruction.

But more than 3,000 miles away from the executive photo ops, more trees were being cut down. Satellite mapping shows many new areas where there has been significant deforestation in the past year, particularly in Ivory Coast. In the south-west region alone, 13,748 hectares (34,000 acres) of forest have been lost in 2018 – equivalent to 15,000 football fields, more than the 13,000 lost there in 2016.

Governments have failed to stop it, and companies are still buying cocoa from “dirty producers” who continue to cut down the few remaining patches of rainforest, according to Chocolate Greenwashing, a Mighty Earth report released on Friday.

“Companies have talked the talk but not walked the walk,” said Etelle Higonnet, the report’s lead author. She warned that “peak deforestation danger season”, the time of year when most trees are cut down, will begin within weeks. “The time for shilly-shallying is over,” she said. “Government and industry need to commit manpower and resources to solve the problem right now.”

At the moment, deforestation is worst in the far west of Ivory Coast, in areas such as Goin Debe and Cavally, the maps show. If nothing is done, Goin Debe’s forests will disappear entirely by 2071 and Cavally’s “protected” forest by 2061, Mighty Earth said. The country has lost 90% of its forest since independence in 1960.

Farmers who continued to cut trees down said they could still sell their cocoa openly without any repercussions.

In Ghana deforestation continues inside Tonton, Tinte Bepo and Tano Ofin forest reserves, and unless the land is immediately restored, cocoa grown on it will probably find its way to the supply chains of big companies such as the Singapore-based agribusiness Olam, Mighty Earth said.

Cocoa is mostly grown on small plots of land by individual farmers, who sell it on to cooperatives and middlemen, who in turn sell it to big companies. This makes it more difficult to track cocoa beans down to the farm they were grown on and to monitor their practices.