South Yorkshire Police has already referred itself to the Police Complaints Commission over its involvement in the "Battle of Orgreave".
But they say any inquiry would take some time because of how long ago the events took place.
Fighting broke out between miners and police at Orgreave Colliery during the miners' strike in 1984.
More top news
Sam Burgess is ready to show what he can do in rugby union following his code switch, after defending his decision to leave league
Lunchtime weather update with Kerrie Gosney
Halloween marks the last day of October & probably one of the warmest on record. Temperatures are expected to rise 5-6 degrees above average