RABAT- London-listed mining company Emmerson Plc said on Tuesday it had received a licence from authorities in Morocco giving it exclusive rights to develop a $400 million potash plant.

The mine, near the city of Khemisset, 94 kilometres (58 miles) east of the capital Rabat, has the potential to produce up to 735,000 tonnes of muriate of potash and 1 million tonnes of de-icing salt a year, a feasibility study showed in the summer.

The company plans to start building the potash mine, Africa's largest, by the end of 2021 and expects to start production in late 2023, Chief Executive Graham Clarke told Reuters.

The potash will be exported through the port of Casablanca, providing easy access to the main markets, he said.

The company said the project would increase Moroccan mineral exports by 8% and generate up to $63 million a year for the Moroccan government in taxes.

(Reporting by Ahmed Eljechtimi. Editing by Mark Potter) ((ahmed.eljechtimi@thomsonreuters.com;))