BEIJING- China's SDIC will buy Canadian fertiliser supplier Nutrien's 28 percent stake in Arab Potash Co for $502 million, the Chinese state-owned company said on Monday, continuing its overseas expansion.

SDIC Mining Investment Co, a subsidiary of China's State Development and Investment Corp (SDIC), will become the majority shareholder in Arab Potash after the transaction, SDIC said in its statement.

China is the top consumer of potash fertiliser and also the top market for Arab Potash.

The agreement signed between SDIC and Nutrien will further reduce China's reliance on potash imports and guarantee its food security, the statement said.

Canadian fertiliser and farm supply dealer Nutrien had begun talking to prospective buyers of its stake in Arab Potash in February.

SDIC is one of China's fastest-growing state-owned enterprises, with investments in power, mineral and financial markets. It has been expanding in the agriculture sector in recent years, with a push into the corn-based ethanol industry. 

(Reporting by Hallie Gu and Dominique Patton Editing by Kirsten Donovan and David Goodman) ((Hallie.Gu@thomsonreuters.com; +86 10 6627 1250; Reuters Messaging: hallie.gu.thomsonreuters.com@reuters.net))