* Decision expected since last October
* Review requested by Merck subsidiary
* Levels scientifically safe - ministry official (Adds quotes and details)
By Meeyoung Cho
SEOUL, Sept 2 (Reuters) - South Korea has lifted a ban on the use of animal feed additive zilpaterol in beef, opening the door to imports containing the growth enhancer as well as domestic sales of the product.
Seoul said last October that it intended to ease its zero-tolerance policy on zilpaterol-based drugs, such as Merck & Co Inc's Zilmax, after a risk assessment fould it could be permitted at certain levels.
Many European countries as well as China ban the import of zilpaterol-fed beef due to concerns about side effects of the additive, which is used to aid growth in the weeks before animals are slaughtered.
South Korea last year suspended some U.S. beef imports for more than two months after traces of zilpaterol were found in two shipments.
An official at South Korea's food ministry confirmed on Tuesday that imports of beef muscle with 1 part per billion (ppb) of zilpaterol, 5 ppb in beef liver and 10 ppb in beef kidney had been approved as of late last month.
"The approved levels are scientifically safe even if consumers have them for the rest of their lives," the official told Reuters by phone. "The decision has come after asking farmers via months of public notices."
He noted the approved levels were lower than in other countries, such as the United States, which permits 12 ppb of zilpaterol in beef liver.
South Korea delayed the decision to lift the ban for a month earlier this year after a request from China. The reason for the request was not known, the ministry official said on Tuesday.
South Korea is a major importer of beef from Australia, the United States and New Zealand.
Zilmax was approved by the U.S. Food and Drug Administration in 2006. South Korea's assessment of its ban was carried out at the request of Merck's subsidiary MSD Animal Health Korea.
Reporting by Meeyoung Cho; Editing by Richard Pullin