Fertilizer maker CF Industries Holdings Inc. said Monday that it is in preliminary discussions with competitor OCI N.V. on a potential combination involving some of that company's businesses.

Deerfield, Illinois-based CF Industries said in a written statement that it would provide no further comment at this time.

Netherlands-based OCI also released a statement on Monday confirming that "it is currently holding discussions about possible combinations or transactions," but it did not name any specific company.

A deal could be worth billions. CF's market capitalization is more than $16 billion, and OCI's more than $7 billion.

Shares of CF rose nearly 10 percent Friday afternoon after reports first surfaced of possible deal talks. Oci shares are up more than 15 percent Monday on the Euronext Amsterdam exchange.