Mars has pledged to buy 100,000 tonnes of UTZ Certified sustainable cocoa in a bid to source only sustainable cocoa by 2020.

In April, it became the first confectioner to commit to use only sustainable cocoa to meet its 300,000 tonnes-a-year need, and agreed to buy 100,000 tonnes of Rainforest Alliance-certified beans.

Its latest move would support the UTZ sustainability standard, which is similar to the Rainforest Alliance scheme but includes measures aimed to improve productivity as well as improving farmers' income, it said.

"If we are paying a pricing premium, we want to make sure farmers are adding value," said Mars sustainable cocoa manager Peter van Grinsven. "We want farmers to intensify farming methods and diversify into other crops so they have a stable income."

If production did not intensify, the supply problems currently plaguing cocoa production would become critical, he warned. However, environmental goals often coincided with the need to make production sustainable. Farmers that Mars had worked with had managed to double their yields and thus improve their income significantly, he claimed.

"In Ghana and the Ivory Coast there are billions of hectares planted with cocoa, but in 25 years that will have very low yield as quality falls. In the past farmers have just moved on, but there's not enough new land to do that any more."

Mars said it was looking to work with other major confectionery suppliers including Cadbury and Nestlé to make cocoa production sustainable.