China's largest food company COFCO is to buy 100 percent of the agricultural arm of embattled trader Noble Group, the companies said Wednesday, in the latest move by China to expand its global reach.

COFCO, which says it supplies grain and oil to a quarter of the world's population, bought 51 percent of Hong Kong-based Noble's agricultural subsidiary in April 2014.

COFCO will now spend $750 million to buy the remaining 49 percent of Noble Agri, which trades grain, sugar, cotton and coffee in around 30 countries from South America to the Middle East.

The deal is seen as a move by Noble to avoid having its credit rating downgraded to junk. The company said in a statement it would use the proceeds to repay debt.

"It helps Noble to raise the cash it needed to avert being downgraded to junk status, and also to get rid of liabilities," Bernard Aw, a strategist at IG Asia Pte, told Bloomberg News. "It's critical for Noble to convince investors that it can transform the ailing company."

The acquisition is the latest move by China's state-owned companies to expand abroad, usually through purchasing existing foreign businesses.

"The acquisition will greatly accelerate COFCO's internationalisation and global positioning," its chairman Ning Gaoning said in a statement.

"COFCO is... still bullish on the long-term performance upon the integration of Noble Agri into COFCO Corporation despite the depressed global agricultural commodity market for the time being."

Noble Agri will be renamed COFCO Agri on completion of the deal.

COFCO currently has over 330 branches across the globe and total assets of $71.9 billion, according to its website.

The deal is subject to shareholder approval, Noble said.