Fifa’s disciplinary committee is believed to be examining the build-up to England’s World Cup qualifying game against Scotland at Wembley.
The display of poppies on big screens, the minute’s silence, playing the Last Post and handing poppy t-shirts to the crowd could now be assessed.
Both Football Associations have been charged for wearing poppies in the match on Armistice Day on 11 November.
Rules forbid “political” statements on shirts.
The booing by supporters during the national anthems and items thrown on to the pitch, allegedly from the section where Scotland fans were sitting, is also understood to be under review.
A Fifa spokesperson said: “We can confirm that the disciplinary committee has opened proceedings on this matter. Please understand we cannot comment further at this stage nor speculate on any outcome or provide an estimated timeline.”
England and Scotland players wore black armbands bearing a red poppy despite failing to get clearance from Fifa.
World football’s governing body turned down a request by both teams to wear the traditional symbol marking Armistice Day.
Fifa said it did not ban the display of poppies and that any such claim was “a distortion of the facts”.
The rules are laid out by the International Football Association Board (IFAB) and any breach is dealt with by Fifa’s disciplinary committee – which Fifa says is an independent body.
Fifa added it could not pre-judge what symbols would constitute a breach of rules.
A points deduction is the most serious sanction available but a fine is considered to be more likely.
The British FAs would then have an opportunity to challenge that fine via Fifa’s appeals process and a further chance to appeal at the Court of Arbitration for Sport – a course of action that would probably cost more than the fine.