Demand for crisps, bread, lipstick and soap could drive orang-utans to extinction, research suggests.
The UK alone imports nearly a million tonnes of palm oil a year for use in such products, but campaigners say plantations for it destroy rainforests.
Friends of the Earth and international ape conservation groups warn in a report that 90% of the animals' habitat in South East Asia has been wiped out.
Their research claims the apes could become extinct within 12 years.
The report, the Oil for Ape Scandal, said palm oil plantations have now become the primary cause of the orang-utans' decline in Malaysia and Indonesia.
Some experts estimated 5,000 orang-utans perished as a result every year.
The research claimed at least 84% of UK companies failed to take effective action to ensure they do not buy palm oil from destructive sources.
Ian Redmond, chairman of the Ape Alliance, said if the government failed to act, "it is we who will have to explain to our children that the orang-utan became extinct because of corporate greed and a lack of political will".