Below-average rainfall in Ivory Coast last week has raised fears of a cocoa supply shortage in the coming months and a weak end to the April-to-September mid-crop, farmers said on Monday.

The world's top cocoa producer relies on regular downpours during the rainy season from mid-March to late October. However, farmers said that a lack of rain could hamper crop development in August and September.

Farmers said the harvest would be strong from mid-May to late June, adding that plenty of pods were ripening on trees. The quality of beans was in line with the mid-crop expectation, with 110 to 120 beans per 100 grams, compared with 90 to 105 for the main crop, they said.

But concerns remain over the crop further out.

"The trees need a lot of rain. If the lack of rain continues, it will not be good," said Maurice Loba, who farms on the outskirts of the western region of Soubre, at the heart of the cocoa belt.

Data collected by Reuters showed rainfall in Soubre was 8.6 millimetres (mm) last week, 18.8 mm below the five-year average.

In the southern regions of Agboville and Divo, as well as the eastern region of Abengourou, rainfall was well below average. Rainfall was also below average in the central regions of Bongouanou and Yamoussoukro.

Although rainfall was above average in the centre-western region of Daloa, which produces a quarter of Ivory Coast's cocoa output, farmers said they were likely to be short of beans by late-June to July.