COFCO Corporation bought another 142 million shares of China Mengniu Diary Co Ltd for around HK$3.59 billion ($461 million), raising its stake in the dairy producer to 28.04 percent, the Shanghai Securities News reported Friday.

COFCO may have bought the shares from Yinniu, Jinniu and a trust fund founded by interests under Concert Party Agreement, including Niu Gensheng, the former chairman and founder of Mengniu, which is China's largest dairy producer, according to a previous media report.

A Deutsch Bank report also confirmed that, saying the sellers are not institutional investors.

It means that Niu transferred all his shares after he resigned as chairman.

Mengniu said previously that Niu resigned to focus more on charity.

COFCO, together with Hopu Investment Management, bought 20 percent of Mengniu for HK$6.1 billion ($783 million) in 2009, making COFCO the largest shareholder of Mengniu since then, the paper said.

COFCO said previously that it will only act as a strategic investor without involving itself in business management, according to the paper.