Exports of cocoa and coffee from Ivory Coast remained blocked by a dock workers' strike on Friday and exporters said they feared the quality of beans held up at the ports could deteriorate in the humidity.

It was the fifth day of the stoppage at Abidjan and San Pedro, the two main ports of the world's top cocoa producer.

The day workers' union Sytrajop-CI called its members out on indefinite strike on Monday to demand better working conditions and higher salaries, after talks with employers broke down.

"We still can't do anything here. The dockers are refusing to work and are threatening to chase off any other employees who try to work," said the sales director of a European export company based in Abidjan.

Although the strike was taking place at the tail end of the October to March main crop, when arrivals at ports were falling off anyway, several thousand tonnes of cocoa and coffee were blocked aboard trucks parked by idle port warehouses.

"It's true that there isn't much cocoa arriving at the moment but we're worried about the quality which is already not very good," the export company sales chief said.

"With prolonged storage aboard the trucks, combined with the rain and the sun, the beans are going to heat up and rapidly rot. That's our biggest worry." he added.

A representative of the striking day workers' union Sytrajop-CI, Fidele Dogba, complained that neither the export companies nor the authorities had been in touch with the union to discuss a possible settlement to the stoppage.

"We warn those who might try to use other outside workers that we'll chase them away by all means possible," he said.