HONG KONG, Dec 9 (Reuters) - Buyout firms KKR & Co LP and CVC Capital Partners are among the suitors that have placed preliminary bids for U.S.-based Tyco International Inc's South Korean unit, a business valued at about $1.6 billion, people familiar with the matter said.

Asia-focused private equity firms Affinity Equity Partners and MBK Partners have also placed bids for the security systems company, the sources added.

ADT Caps Co, as the South Korean business is known, had earnings before interest, depreciation and amortization (EBITDA) of $160 million at the end of Sept. 2013, according to U.S. accounting. The business is expected to fetch $1.6 billion, based on a ten times EBITDA multiple, the sources added.

Morgan Stanley is advising Tyco on the sale. The sources declined to be identified as the process is confidential.

KKR, MBK and CVC declined to comment. Tyco and Affinity did not respond to emails seeking comment.