March 15 (Reuters) - Southeastern Grocers LLC, which operates supermarket chains Winn-Dixie and Bi-Lo, said on Thursday it is preparing to file for bankruptcy and would shutter 94 underperforming stores.

"We conducted a thorough review of our strategic options," Chief Executive Anthony Hucker said. The company said it plans to file with the Delaware Bankruptcy Court by the end of this month.

The restructuring would reduce overall debt levels by more than $500 million and help the Jacksonville, Florida-based company invest more in its business, Southeastern said, adding that it would continue to operate 582 stores.

Reuters had reported last month that Bi-Lo was planning to close at least 100 stores in a potential bankruptcy, citing two people familiar with the matter.

Margins of supermarkets have taken a hit from growing competition from big box stores, including Wal-Mart Stores Inc and online options such as Amazon.com Inc.

Southeastern Grocers operates its stores in Alabama, Florida, Georgia, Louisiana, Mississippi, North Carolina and South Carolina. (Reporting by Arunima Banerjee in Bengaluru; Editing by Lisa Shumaker)