Michael Usi, a Malawian cabinet minister with responsibility for the environment, said he has ordered a review of all carbon credit projects in the country.

Usi’s comments come after Malawian President Lazarus Chakwera on June 23 announced the creation of a government agency to oversee the trade and marketing of the offsets in the country.

“Those projects which started a long time ago must be revisited,” Usi said at a conference in Victoria Falls, Zimbabwe, on Friday.

Malawi has joined Zimbabwe and Kenya in seeking to regulate the production and trade of carbon credits with those nations saying the government and local communities aren’t deriving enough benefit from the industry.

Zimbabwe in May ordered that all programs be scrapped and then be renegotiated with the government, with a view to giving the state 50% of the revenue.

A single carbon credit represents a ton of climate-warming carbon dioxide or its equivalent that’s either removed or prevented from entering the atmosphere. The credits are bought by companies to offset their greenhouse gas emissions as tighter legislation forces them to do more to slow global warming.

The global trade in carbon offsets is projected to grow to as much as $1 trillion within 15 years from $2 billion now, according to estimates from BloombergNEF.

(Updates with detail on Malawi’s plans from second paragraph)