Jan 7 (Reuters) - Merck & Co is in advanced talks to buy cancer drugmaker Harpoon Therapeutics Inc for around $700 million, Bloomberg News reported on Sunday, citing people familiar with the matter.

Merck is discussing paying $23 per share for immuno-oncology company Harpoon, Bloomberg said, representing a premium of 118% to Harpoon's Friday closing price of $10.55.

A deal could be announced within days assuming talks don't fall apart, the report added.

Merck and Harpoon did not immediately respond to Reuters requests for comment.

Harpoon is developing drugs that harness the power of the body's immune system to treat patients suffering from cancer and other diseases. It reported positive data for its lung cancer treatment in early-to-mid stage trial in October. (Reporting by Chandni Shah in Bengaluru; Editing by Subhranshu Sahu)