West Ham United have been given until the end of this week to respond to the FA with their observations on the unrest that marred Saturday's 3-0 home defeat to Burnley, it has been reported.
Four separate pitch invasions interrupted the game at the London Stadium.
And co-owner David Sullivan was hit by a coin and forced to leave the directors' box, as hundreds of supporters congregated below in protest at the club's board (see left).
The FA expects this to be a lengthy disciplinary process.
It could still be a fortnight before any charge is forthcoming, and even longer before the FA announce any sanctions, once an independent commission has heard the case.
West Ham will not be able to side-step any punishment by suggesting they do not organise the stewarding at London Stadium.