Feb 23 (Reuters) - MGM Resorts International disclosed that state and federal regulators were probing a cyberattack on its systems that took place in September and caused a $100 million hit to the company's third-quarter results.

The casino operator intends to respond to the inquiries in due course, a regulatory filing by MGM showed on Friday.

The cyberattack had led MGM to shut down its systems after queues piled up at Las Vegas hotels and slot machines began showing error messages.

Hacking group AlphV has claimed involvement in the breach.

Sources told Reuters in September that AlphV worked with another outfit named Scattered Spider to break into MGM systems and steal data to hold for extortion. (Reporting by Ananta Agarwal in Benagluru; Editing by Krishna Chandra Eluri and Shinjini Ganguli)