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, Sky Sports News has been told.
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.
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.
Sky Sports News understands West Ham will not be able to side-step any punishment by suggesting they do not organise the stewarding at London Stadium.
Even though LS185 is a separate company, which handle stewarding inside the ground, the FA sees West Ham as responsible for the effectiveness of that stewarding.
The FA can only take retrospective, punitive action against a club once an incident has happened.
It is for the London Stadium's Safety Advisory Group to look to future games, and decide what changes are necessary to ensure safety.
Meanwhile, a man voluntarily handed himself into police on Monday regarding the incident. No arrests have so far been made, but the Metropolitan Police have confirmed that the man presented himself to a Hertfordshire Police Station.
His details have now been passed on to the Met. They will interview the man at a later date.