Authorities in the Pacific coast Mexican state of Nayarit say they are investigating the remains of at least 30 people found in a series of clandestine graves.

The Nayarit state prosecutor's office says in a statement that bodies and bones were found.

A state official who was not authorized to speak publicly says the remains of at least 30 people were found in three clustered graves in the municipality of Xalisco.

The official says they were in an area beside a stream that is difficult to access. Some families searching for missing loved ones found remains on Saturday after being tipped off by local residents.

The official says there was a spike in disappearances in the region from June to September after the area's most powerful organized crime group splintered.