The United States will file a formal objection Wednesday to Bolivia's proposal to end the ban on coca leaf-chewing specified by a half-century-old U.N. treaty, according to a senior U.S. government official. "We hope that a number of other countries will file as well," the official told The Associated Press on Tuesday. He spoke on condition he not be further identified, citing the topic's political sensitivity.

Despite being stigmatized as the raw material of cocaine, coca leaves have been chewed by indigenous peoples in the Andes for centuries.

A mild stimulant, the leaves have deep cultural and religious value in the region. Chewed or consumed as tea, coca counters altitude sickness, aids digestion and suppresses hunger and fatigue.

Jan. 31 is the deadline for nations to raise objections with the United Nations to Bolivia's proposed amendment to the 1961 Single Convention on Narcotic Drugs to remove language that obliges signatories to prohibit the chewing of coca leaves. If none are registered, it would automatically take effect.

Bolivia's leftist government, which is led by a former coca growers union leader, and its supporters contend the language it wants removed is discriminatory.

The convention's stipulation that coca-chewing be phased out within 25 years after it took effect in 1964 is based on a "blatantly racist" 1950 report, according to liberal advocacy groups Washington Office on Latin America and the Transnational Institute.

The Bolivian proposal would leave in place language that made coca leaves a controlled substance, said Pablo Solon, the country's U.N. ambassador.

Bolivian President Evo Morales launched a global campaign after his 2005 election seeking to declare coca licit, chewing it at international forums and presenting coca leaf-embossed art works and musical instruments to foreign officials including then-U.S. Secretary of State Condoleezza Rice.

"How can it be possible that the coca leaf, which represents our identity, which is ancestral, be penalized," Morales, an Aymara Indian, told reporters Friday before dispatching his foreign minister to Europe to lobby for the proposal.

Washington argues that the amendment would open the nearly 50-year-old convention to attack by any U.N. member nation that would seek to exclude for parochial reasons one of the 119 substances the convention classifies as narcotics, submitting them to strict controls.

Trying to carve out such exceptions "over the long term is not good for the planet's efforts to control and eventually solve the problem of drug abuse," the senior U.S. official said, adding that Washington also fears it could open a Pandora's box of legal challenges to drug crimes in the United States.

The official said "there is evidence to suggest that a substantial percentage" of the increased coca production in Bolivia over the past several years, registered in U.N. surveys, "has indeed gone into the network and the marketplace for cocaine."

The U.S. arguments are outmoded and "there is not a single scientific study left that shows coca is a dangerous substance," said Paul Gootenberg, a professor at the State University of New York at Stony Brook and author of "Andean Cocaine: The Making of a Global Drug."

"Traditionally the argument was that coca was basically cocaine and could be used illicitly to distill cocaine. But that was never realistic," he said, noting that it would take 440 pounds (200 kilograms) of coca leaves to produce 2.2 pounds (a single kilogram) of cocaine. "It has never happened and it never would. It doesn't make any sense from a smuggler's perspective."

Washington is filing its objection after weeks of lobbying other nations and had hoped others would object first - or at least simultaneously - so as not to hurt its attempts to mend relations with Bolivia, Martin Jelsma of the Transnational Institute told the AP.

Morales expelled the U.S. ambassador and agents of the Drug Enforcement Administration in late 2008, accusing them of inciting the opposition.

Two nations - Macedonia and Colombia - recently filed objections but withdrew them, Bolivia's charge d'affaires in Washington, Erika Duenas, told the AP. Egypt did the same a year ago, Jelsma said.

The senior U.S. official said Washington initially planned to file its objection last Friday but delayed after some progress on efforts to restore diplomatic ties with Bolivia.

"We regret the confusion. Our posture and position never changed, but we were hoping not to work at cross purposes with an equally laudable objective," the official said, adding that Washington had hoped the EU would forge a single unified position by now.

Contacted by the AP, officials of several EU nations said Tuesday they either did not have an opinion or had not arrived at a decision.

Spanish Deputy Prime Minister and Interior Minister Alfredo Perez Rubalcaba said he had "no stance on this question."

A German official said "our position is currently being worked out." And a spokesman for Portugal's foreign ministry, also speaking on condition of anonymity because of the subject's sensitivity, said a joint EU position was expected Jan. 25.

Carel Edwards, who retired six months ago as head of the EU Commission's drug policy unit, said many European nations currently consumed by economic woes "do not want to be seen to be unhelpful to the U.S. over an issue that is by no means at the top of their own domestic agendas."

They understand, he said, that given the extreme violence of the drug war in neighboring Mexico, "combined with the rather simplistic and populist views held by the general public on (narcotics) in the U.S., it is difficult for any U.S. administration to go along with the Bolivian request."

Gootenberg said the United States is encountering greater resistance these days to its position on coca leaf.

"As global cultural rights have come to the forefront of the U.N.'s agenda (its) anti-coca policy is a glaring contradiction," he said.

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Associated Press writers Carlos Valdez in La Paz, Bolivia, Ciaran Giles in Madrid, Barry Hatton in Lisbon, Portugal, and Juergen Baetz in Berlin contributed to this report.