Bolivia and Peru have defended the continued, traditional use of coca leaves after they were criticised by a UN drugs agency report.
The UN lists coca as a controlled substance like cocaine or opium
The UN report concentrated on coca cultivation as the basis for cocaine production, they said.
It failed to recognise that coca leaves had been used by indigenous peoples for medicinal and religious purposes for centuries, they added.
Peru and Bolivia are second only to Colombia as world cocaine producers.
Peru said a balance was needed between allowing cultivation for traditional uses while preventing it for cocaine production.
"One of the principles of humanitarian law is the respect of traditional customs, recognised by the national constitution," said Jose Belaunde, Peru's foreign relations minister.
"The United Nations lacks respect for the indigenous people of Peru and Bolivia who have used the coca leaf since forever," said Peruvian Congresswoman Maria Sumire.
"For indigenous people, coca is a sacred leaf that is part of their cultural identity," she said.
The International Narcotics Control Board released an annual report on Wednesday that reminded the two governments that use and possession of coca leaves, the main ingredient in cocaine, were limited to medical and scientific purposes.
The two countries should "abolish or prohibit activities... such as coca leaf chewing and the manufacture of coca tea", the report said.
People in the Andes use coca leaves to alleviate hunger and tiredness, for medicinal purposes and in religious rituals.
UN conventions list coca as a dangerous controlled substance, along with cocaine and opium.
Bolivian President Evo Morales has been lobbying for it to be taken off the list when the UN Commission on Narcotic Drugs meets in 2009.