WASHINGTON (Reuters) - Russia will begin to block imports of U.S. poultry as of Jan 1. because of concerns about a commonly used chlorine treatment, U.S. government officials and a Russian news agency said on Thursday.

Russia plans to proceed, over U.S. objections, with a new law prohibiting chlorine as an anti-microbial treatment in poultry production, said Katie Gorscak, a spokeswoman for the U.S. Agriculture Department.

“Since chlorine has been used as an anti-microbial treatment for poultry in the United States for more than 25 years, this resolution effectively blocks U.S. exports of poultry to Russia, has a devastating impact on the U.S. poultry industry and trade, and raises the costs of poultry products for Russian’s consumers,” Gorscak said.

U.S. and Russian officials have agreed to hold further technical talks on the issue “as soon as possible,” but are still working to finalize dates, she said.

The United States believes Russia’s new regulation is unjustified because of “overwhelming scientific evidence” showing chlorine is safe and effective disinfectant for use in poultry, Gorscak said.

Jim Sumner, president of the USA Poultry and Egg Export Council, said he hoped poultry already headed to Russia would be allowed to enter, even though longer-term prospects were uncertain.

“There may be about 30,000 tonnes (of U.S. poultry) en route or at the port in Russia, but we are optimistic that it will be allowed to enter, based on the assurances earlier from the Russian Veterinary Service,” Sumner said in an e-mail to Reuters.

“Future exports are questionable, however, until this issue gets resolved,” he said.

The issue has threatened the top market for U.S. poultry -- worth $801 million in 2008 -- for more than a year.

A week ago, Russian veterinary officials indicated the poultry trade would continue. Russia also recently moved to ban pork from all but six U.S. processing plants because of a dispute over standards for antibiotic residues.

Poultry processors in the United States routinely use chlorine rinses to kill pathogens that can cause food poisoning.

There are no detectable residues left from the treatments, which have long stalled U.S. poultry exports to the European Union. The United States has complained about the EU ban at the World Trade Organization.

The new rule will not affect Russia’s imports of EU poultry, said Gennady Onishchenko, head of the consumer protection agency Rospotrebnadzor, in an interview with Russian news agency Interfax.

“It’s not a ban on anyone’s quotas. Just treat your meat the way our national legislation prescribes and no one will object to its imports,” Onishchenko said.

Russia’s requirements will restrict the use of chlorine in poultry plants to 0.5 parts per million, which Sumner said is 10 times lower than the standard chlorine content in U.S. municipal drinking water.

“The U.S. industry will be unable to comply with Russia’s requirements,” Sumner said.

Technical and health-related barriers have become a thorn in U.S.-Russia meat trade, increasing as Russia moves to boost its domestic meat production and decrease its reliance on imports.

Russia, which does not belong to the WTO, lowered its quota for U.S. poultry this year. But industry officials believe the chlorine issue will be worked out because Russia cannot yet produce enough to meet its needs.

“I think they will still need us for chicken,” Rich Nelson, analyst at the agriculture advisory firm Allendale Inc, said in response to the possible ban.

“I think they will need our chicken for at least another year,” Nelson said.