Mars Inc. is strenuously denying that it has been trying to evade a surcharge on cocoa imposed by the two African nations that generate most of the world’s supply.

Ivory Coast and Ghana started charging a “living income differential” (LID) of $400 a ton on cocoa beans starting with the harvest this fall. The money would ostensibly go to improve the living situations of farmers and harvesters, many of whom are children working under conditions that amount to slavery.

The two nations, which between them grow about 70% of the world’s cocoa supplies, claimed in November that Mars, Hershey and some other large chocolate purchasers were seeking to evade the LID. Specifically, Mars was accused of altering its purchases of cocoa butter to get around the surcharge.

Mars, which had announced its support when the LID initiative was unveiled, denied the allegation in a Dec. 1 letter to local regulators. “We remain extremely concerned by these false accusations which, while may be true for other players in the industry, are in no way reflective of Mars,” Michelle O’Neill, global vice president of corporate affairs for cocoa at Mars, said in the letter.

The stakes are high, as Ivory Coast and Ghana are threatening to suspend the purchasing licenses of any chocolate users who don’t pay the surcharge.