Meat from wild primates killed in Africa is increasingly being consumed in the west, according to a new survey.
Published in the New Scientist, the University of California study found that illegal markets exist in major western cities including London, New York and Paris.
Primate meat on sale, which counts for a third of the illegal international trade in bushmeat, includes chimpanzee, gorilla and duikers (small antelopes).
Fifteen volunteers recorded the amount of meat on sale in illegal markets in Brussels, Chicago, London, New York, Montreal, Paris and Toronto, discovering that over 6,000kg of meat passes through these markets each month.
It is thought that this figure for primate meat could be higher as customs officials in the US and UK put all illegal meat together in their reports.
"I was shocked that open markets sell large quantities of African bushmeat in major cities outside of Africa," said wildlife biologist Justin Brashares, who conducted the research.
"I have 27 records of chimpanzee and gorilla parts being sold in the markets," Mr Brashares told the New Scientist.
"In each case it was not a complete body, but a hand, leg or, in two cases, a head."
Glyn Davis, director of conservation for the Zoological Society of London, said that the bushmeat trade is huge and supports thousands of people in Africa, but is difficult to be maintained in a sustainable manner.
Although Mr Davis said that cane rats and duikers could potentially be harvested sustainably to support local people, he added that this is "very different to harvesting large mammals such as great apes and elephants" as that would be "very hard" to be sustainable.