By Mark Doyle BBC Africa affairs analyst

New research says that reports of children being traded as "cocoa slaves" on plantations in West Africa have been heavily exaggerated.

Last year, Western lobbyists severely criticised multinational chocolate companies for using cocoa cultivated by child slaves.

But detailed research by the Nigerian-based International Institute for Tropical Agriculture says that while child labour is a major problem on farms in poor countries, very few of the children were traded or could be described as slaves.

Most children interviewed by the institute gave the realistic, but rather undramatic, explanation that they were searching for work and a better life.

Misleading

Last year's outcry evoked the spectre of wicked traders and uncaring African governments.

Ivory Coast produces half the world's cocoa

But the new research found that in the world's leading cocoa producer, Ivory Coast, none of more than 2,000 child workers questioned said they had been forced to leave their homes.

All of them knew that they were destined for cocoa farms.

David Mobray, of the institute, said that in some cases it might seem as though a child had been trafficked when further investigation showed they might not have been.

"It doesn't mean, mind you, that the child is not at risk," he said. "That is the most important thing."

He said that children might be at risk because they may not be getting the educational opportunities they would otherwise have had.

The new research shows, unsurprisingly, that poor families are often forced to sacrifice education for work, especially as cocoa prices are falling.