Geneva, May 19 - Production and sale of counterfeit drugs is on the rise in rich and poor countries, with more unwary consumers buying them over the Internet, experts warned Wednesday.

Fake or substandard versions of medicines are often hidden in cargos taking circuitous routes to mask their country of origin as part of criminal activity worth billions, they add.

"They put people at risk of harm from medical products that may contain too much, too little, or the wrong active ingredient and/or contain toxic ingredients," said Margaret Hamburg, head of the U.S. Food and Drug Administration (FDA).

"Counterfeiting is growing in complexity, scale and geographic scope," she said in a speech to the annual ministerial meeting of the World Health Organization (WHO).

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