"This entitles the company to subscribe for 15,553,600 ordinary shares in Kahawatte Plantations, 19.47 percent of the shares representing the ultimate stated capital if the rights issue is fully subscribed," it said.
The company plans to invest another 233.3 million rupees to subscribe for the ordinary shares at 15 rupees a share.
Ceylon Tea Services holding company is MJF group which is also the holding company of Forbes Plantations.
Sri Lanka's stock market has been on the upswing this year, hitting new highs, although it suffered a correction this week.
Tea prices have also been strong on the back of strong demand, boosting tea plantations profits.