(Reuters) - Family Dollar Stores Inc (>> Family Dollar Stores, Inc.) said certain state attorney generals have notified the company that they will investigate larger rival Dollar General Corp's (>> Dollar General Corp.) takeover bid over competitive concerns.

Family Dollar spurned Dollar General's sweetened $9.1 billion all-cash bid earlier this month, saying the offer still did not address antitrust concerns. Family Dollar instead said it was sticking with a lower $8.5 billion cash-and-stock offer from Dollar Tree Inc (>> Dollar Tree, Inc.).

After being spurned twice, Dollar General took its bid hostile and approached Family Dollar shareholders directly.

Dollar General has offered to sell up to 1,500 stores and to pay $500 million as break-up fee if the deal failed to clear antitrust reviews.

Family Dollar said on Friday it notified the FTC about the state attorney generals' plans to investigate the Dollar General bid. (http://bit.ly/1rpt41f)

The company did not name the states involved in the investigation.

(Reporting By Nayan Das; Editing by Sriraj Kalluvila)