* South Korea currently bans controversial animal feed zilpaterol
* Study find feed additive could be permitted at certain levels-official
* Official says awaiting international recommendations on levels
SEOUL, Oct 31 (Reuters) - South Korea plans to end its ban on the animal feed additive zilpaterol early next year, a senior food ministry official said on Thursday, opening the door to beef imports containing the growth enhancer and its domestic sale.
The Asian state has a zero tolerance policy on zilpaterol-based drugs and earlier this month suspended some U.S. beef imports after traces of the feed additive were found in two shipments.
Son Seong-wan, director of livestock products standard division at South Korea's food ministry, said in an interview that the government's risk assessment found the feed additive could be permitted at certain levels.
The feed additive has been under global scrutiny since a video emerged in the United States in August showing animals struggling to walk and with other signs of distress after taking a growth drug.
Merck & Co produces Zilmax, which contains zilpaterol and was approved by the U.S. Food and Drug Administration in 2006, and South Korea's move could open the door for its sale from early next year, Son said.
The South Korean assessment was done at the request of Merck's subsidiary MSD Animal Health Korea. An offical from the local unit said it had been put in the request in June last year.
South Korea is among a number of Asian countries, including China, that have not approved zilpaterol for use in meat. Many European countries ban the import of zilpaterol-fed beef due to concerns about the side effects of additives.
"Once the level tolerated is established early next year, domestic sales of Zilmax will be possible immediately," Son said.
He declined to specify what level would be permitted, but said the food ministry was awaiting international recommendations on zilpaterol due to be released by a Joint FAO/WHO Expert Committee on Food Additives (JECFA) next month.
CARGILL BANS ZILMAX
Son and an official at MSD Animal Health Korea said the United States tolerated 12 parts per billion (ppb) of zilpaterol in beef liver, while Japan allowed 10 ppb in beef muscle.
Merck said on Tuesday it planned to resume sales of Zilmax in the United States and Canada after it completes an audit of how the product is used.1
Merck had halted sales of the muscle-building drug in August after Tyson Foods Inc. said it would stop accepting Zilmax-fed beef given some cattle were observed arriving for slaughter with signs they were having difficulty walking or moving. Merck has said it stands behind the safety of its product, but the pause added to global concerns over its use.
But Cargill Inc, one of the world's largest beef processors, said on Wednesday it would not accept Zilmax-fed beef into the Cargill supply chain "until we are 100 percent confident the animal welfare issues are resolved."
Cargill said its ban on Zilmax applies both to beef it processes, as well as to cattle in its own feed lots. In addition, Cargill said it will not use Zilmax-fed beef "until Asia and other trading partners accept it in their markets."
Merck did not immediately respond to a request for comment on Cargill's action.
(Editing by Ed Davies)