Ghana's main opposition party has reacted with anger after one of its most influential leaders was sentenced to 20 years in jail, with hard labour, for illegal mining offences. The New Patriotic Party (NPP) alleged that the landmark judgement against Bernard Antwi Boasiako, the party's chairman for the Ashanti region, was politically motivated. As well as receiving a jail sentence, Boasiako, who had denied the charges, was ordered to pay more than $10,000 (£7,450) in fines. The NPP politician was found guilty of "assigning mineral rights without approval" and "facilitating an unlicensed mining operation" through his company, Akonta Mining. Ghana is Africa's leading gold producer, but a large portion of the country's waters and environment have been polluted by illegal mining, known as locally as "galamsey".