BEIJING (Reuters) - China said on Wednesday defended its duties on imports of U.S. poultry products as legal, after the United States said it would challenge the policies. "China believes its anti-dumping and countervailing measures on U.S. chicken products are legal and in line with World Trade Organization rules, the Ministry of Commerce said in a statement on its website (www.mofcom.gov.cn). The duties, which became final last year, are widely seen as retaliation for a U.S.