UPDATE 4-Russia may block some N. American meat over ractopamine
* Russian watchdog says U.S., Canada violated import rules
* Concerns over chilled beef, pork products
* Temporary ban could begin Feb. 4
* Russia imports more than $500 mln/yr of US beef, pork
* USTR's office: "concerned" about Russia's actions
By Melissa Akin and Theopolis Waters
MOSCOW/CHICAGO, Jan 23 (Reuters) - Russia may impose a temporary ban on the import of some U.S. and Canadian beef and pork products as of Feb. 4, amid concerns that they may contain a drug used to make animal muscle more lean.
Russia's Veterinary and Phytosanitary Surveillance Service said on Wednesday that both countries were continuing to send chilled meat products to Russia that violated its import rules that require such proteins be free of residues from the feed additive ractopamine.
Such requirements are also in place in Belarus and Kazakhstan, who are partners with Russia in a three-country customs union. Continued...