YAMOUSSOUKRO (Reuters) - Ivory Coast inaugurated on Thursday its first senate, an upper house to the West African nation’s parliament that President Alassane Ouattara called a “chamber of wisdom” but which the opposition says will tighten his grip on power.

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Its creation was a provision of a new constitution enacted in 2016. Ivory Coast’s main opposition groups boycotted the referendum that approved the charter as well as polls last month that elected 66 members to the 99-seat body.

“The senate is installed. It is an important chamber for the rooting of democracy,” said Ouattara, addressing the newly elected lawmakers bedecked in green, white and orange sashes - the colours of the Ivorian flag. “It is a chamber of wisdom.”

The senate will be headed by Jeannot Ahoussou-Kouadio, a former prime minister and member of the Democratic Party of Ivory Coast (PDCI), the main coalition partner of Ouattara’s Rally of the Republicans (RDR).

Ouattara is seeking to solidify the alliance as Ivory Coast - the world’s top cocoa producer - heads towards presidential elections in 2020.

Ivory Coast has emerged as one of Africa’s fastest-growing economies in the wake of a decade-long political crisis that was capped by a brief 2011 civil war.

While Ouattara, a former senior International Monetary Fund official, has received praise for the revival, he faces growing criticism for not doing enough to heal the deep divisions left over from the crisis years.

The 2016 constitution was seen by many analysts and diplomats as a missed opportunity to foster constructive political dialogue between Ouattara’s backers and supporters of former President Laurent Gbagbo.

Gbagbo is currently on trial before the International Criminal Court accused of crimes against humanity committed during the 2011 conflict.

Ruling coalition members say that the senate will improve checks and balances within the government. But opposition members say the body - a third of whose seats will be appointed by the executive - is little more than a power grab.

The ruling coalition already dominates the existing National Assembly, which will become the lower house of parliament.

“This is the worst of democratic retreats. It’s abhorrent,” Boubakar Kone, a spokesman for one of the two rival factions of Gbagbo’s Ivorian Popular Front (FPI) party, told Reuters.

Ouattara has yet to name the final 33 senators, though it is expected the list will include some opposition figures.