A court on July 18 ordered the liquidation of the SAF-Cacao group of companies, which includes exporter CIPEXI and processor CHOCO-IVOIRE, over unpaid debts to the Ivorian marketing board, the Coffee and Cocoa Council.

The three officials from different lenders, who asked not to be named, told Reuters that the group owed Ivorian banks between 150 billion and 155 billion CFA francs ($268 million to $277 million).

The Ivorian banking association has written to Prime Minister Amadou Gon Coulibaly to ask for assistance, the officials said.

"We clearly indicated the systemic risks for the Ivorian banking sector if nothing is done to help us," one of the officials said. "We must act now. Not in six months or a year. It's urgent."

Although 25 banks operate in Ivory Coast, the sector is dominated by the five largest, which represent around 60 percent of banking system assets. Four of those are owned by foreign banks with activities across the region.

They include the local units of France's Societe Generale , Togo-headquartered Ecobank as well as Banque Atlantique and SIB, controlled by Moroccan lenders BCP and Attijariwafa respectively.

The SAF-Cacao group purchases around 150,000 to 200,000 tonnes of cocoa annually and is thought to have around 50,000 tonnes of cocoa beans in its warehouses.

That cocoa technically belong to the banks, but the stocks, some of which are up to two years old, are believed to be of very poor quality and therefore of low value.

An International Monetary Fund analysis earlier this year found that lending to the five largest borrowers equated to 98.9 percent of the banking system's total capital, highlighting how hard banks could be hit by just a few defaults.

Cocoa exporters are among the major borrowers in Ivory Coast but last season saw a wave of export contract defaults that have left them unable to pay back their bank loans.

Those outstanding loans coupled with the impact of SAF-Cacao's liquidation could discourage banks from further lending to Ivory Coast's world-leading cocoa sector, bank officials and exporters said.

Though any slow-down in local credit would effect all exporters, it is likely to disproportionately penalise domestic firms and further increase the dominance of large multinationals which typically have access to financing from abroad.

"It will not only slow down buying in the bush but also exports. The banks are like a car's motor oil. It works best when there's oil, otherwise it breaks," one exporter told Reuters.