Indigenous activists in Bolivia have been holding a mass coca-chewing protest as part of campaign to end an international ban on the practice.
Hundreds of people chewed the leaf outside the US embassy in La Paz and in other cities across the country.
Bolivia wants to amend a UN drugs treaty that bans chewing coca, which is an ancient tradition in the Andes.
But the US has said it will veto the amendment because coca is also the raw material for making cocaine.
The protesters outside the US embassy also displayed products made from coca, including soft drinks, toothpaste, sweets and ointments.
They were supporting a Bolivian government campaign to amend the 1961 UN Single Convention on Narcotic Drugs to remove language that bans the chewing of coca leaf.
The convention stipulates that coca-chewing be eliminated within 25 years of the convention coming into effect in 1964.
Bolivia says that is discriminatory, given that coca use is so deeply rooted in the indigenous culture of the Andes.
The US is opposed to changing the UN convention because it says it would weaken the fight against cocaine production.
In a statement, the US embassy said Washington recognised coca-chewing as a “traditional custom” of Bolivia’s indigenous peoples but could not support the amendment.
“The position of the US government in not supporting the amendment is based on the importance of maintaining the integrity of the UN convention, which is an important tool in the fight against drug-trafficking,” it said.
The US is the world’s largest consumer of cocaine and has been leading efforts to eradicate coca production in the Andes for decades.
Bolivia is the world’s first biggest producer of cocaine after Peru and Colombia, and much of its coca crop is used to make the illegal drug.
Bolivian President Evo Morales has long advocated the recognition of coca as a plant of great medicinal, cultural and religious importance that is distinct from cocaine.
As well as being Bolivia’s first indigenous head of state, Mr Morales is also a former coca-grower and leader of a coca-growers trade union.
The Bolivian amendment would come into effect on 31 January only if there were no objections.