Japan's Daiichi Sankyo Company Ltd (4568.T) is selling its stake worth up to $3.6 billion in Indian drugmaker Sun Pharmaceutical Industries Ltd (SUN.NS), a person directly involved in the deal said on Monday.

The Japanese company is selling its 8.9 percent stake in Sun Pharma, India's largest drugmaker by sales, via block deals on the Indian exchanges, said the person, who declined to be named as he was not authorized to speak to the media.

Mumbai-headquartered Sun Pharma agreed to buy Indian rival Ranbaxy Laboratories Ltd (RANB.NS) for $3.2 billion in April 2014 from Daiichi Sankyo. As part of the deal, Daiichi Sankyo got 8.9 percent stake in Sun Pharma. 

Daiichi Sankyo said on Monday in an exchange filing that the company's board had approved to sell all or part of its stake in Sun Pharma. The existing business partnership with Sun Pharma will remain unchanged after the deal, it said.