Moscow, Feb 12 (IANS/RIA Novosti): Russia has slapped a temporary ban on US beef and pork imports over what it says is a failure by the US food safety watchdog to guarantee that the shipments are free of the feed additive ractopamine.

Russia's federal food safety agency warned the US, Canada, Mexico and Brazil in late 2012 that their meat imports could be halted should the shipments contain the additive.

Animal rights groups have said that ractopamine, used to stimulate livestock growth and make meat leaner, is prohibited in about 160 countries, including the European Union and the member states of the Customs Union of Russia, Belarus and Kazakhstan.

The US government and the country's meat industry lobby groups insist that ractopamine is safe at acceptable levels established by the international community, including the UN's main food safety body.

A spokeswoman for the White House's chief trade adviser said earlier that the US was "deeply concerned" by Russia's decision to ban US beef and pork imports containing ractopamine, a move Washington believed could hurt bilateral ties.

"These actions threaten to undermine our bilateral trade relationship," said Andrea Mead, spokeswoman for the office of US Trade Representative (USTR) Ron Kirk.

Russia's food safety watchdog Rosselkhoznadzor said the demand for ractopamine documenation from Brazil, Canada and Mexico could be withdrawn if inspections show that these nations' meat exports to Russia match the same criteria as exports to the European Union.

"We plan to cancel the requirement for additional documentation guaranteeing the absence of ractopamine for meat supplies from Canada, Mexico and Brazil in the near future," Rosselkhoznadzor spokesman Alexei Alekseyenko said.

"This will be done if we are sure their system works."

It was not clear when the planned inspections would take place.