Mauritania's liaison officer to Interpol is among several people sent to jail over cocaine trafficking.
Police commissioner Sid'Ahmed Ould Taya was sentenced to seven years in prison for "not acting on a crime brought to his attention".
A French citizen was jailed for 15 years, along with five Mauritanians.
Prosecutors said the men had tried to build a desert runway to import cocaine. West Africa is now a major hub for smuggling drugs to Europe.
Some of those convicted were sentenced to hard labour and fines, on top of the jail terms.
They were allegedly planning to send hundreds of kilos of cocaine to Europe disguised as a fish shipment.
The AFP news agency reports that a total of 14 people were jailed and 18 acquitted.
Lawyers for the accused say they will appeal, according to the Reuters news agency.
Latin American traffickers send cocaine to West Africa on its way to the European market.
Many West African countries have a combination of weak states and high levels of poverty which mean drugs rings can often bribe officials to let them operate.