US Senator Marco Rubio, a Republican and a China hawk, asked for a national security review of plans by GNC to sell itself to Harbin Pharmaceutical Group.

Rubio made the request in a letter to Treasury Secretary Steven Mnuchin. The department leads the inter-agency Committee on Foreign Investment in the United States.

GNC has said it has agreed in principle with many lenders to sell itself to an affiliate of its largest shareholder, Harbin Pharmaceutical, for $760 million in a court-supervised auction, subject to higher bids.