HONG KONG, June 18 (Reuters) - Shares of China Youran Dairy Group Ltd were set to open at HK$6.28 per share in their Hong Kong debut on Friday, down 10% from the initial public offering (IPO) price of HK$6.98 apiece.

The benchmark Hang Seng Index was set to open 0.1% up.

The Chinese raw milk producer, backed by private equity group PAG, raised $643 million in its Hong Kong IPO, with the proceeds to be used to build and buy new dairy farms, to buy dairy cattle stock and for working capital. (Reporting by Donny Kwok; Editing by Muralikumar Anantharaman)