Football Association chief executive Martin Glenn has warned FIFA he will fight any attempt to fine England for wearing poppies in Friday's World Cup qualifier against Scotland, describing the FA's case as "rock solid".

Both teams are set to defy FIFA's ban on messages that it considers commercial, personal, political or religious by wearing black armbands with embroidered poppies to mark Armistice Day.

The FA and Scottish FA had hoped to do this without punishment - as they and the Football Association of Wales had done in three November friendlies in 2011 - but the new regime at world football's governing body has refused to sanction this exception to the game's laws.

This was confirmed by FIFA general secretary Fatma Samoura during a visit to London last week, when she reiterated law four, paragraph four, that states players' equipment must be free from messages that could cause offence.

Samoura pointed out this law was brought in by the International Football Association Board, which is comprised of the four British home nations and FIFA, and said it must be "applied uniformly" for it to have authority.

The former United Nations diplomat did not say the English and Scottish would definitely be punished for flouting this law but recent decisions by FIFA's disciplinary committee suggest a fine is likely.

The same would apply to the Welsh FA if it decides to go ahead with its plan for players to wear armbands with poppies on them for the game against Serbia in Cardiff on Saturday, while it is unclear what punishment Northern Ireland will face for wearing plain black armbands against Azerbaijan in Belfast on Friday.

But speaking to journalists at a Sport Industry Breakfast Club event in London, Glenn said: "If (FIFA) fine us, we'll contest. They have much bigger problems they should be concentrating on.

"I'm confident our legal position is right and our moral position is right. Our case is absolutely rock solid."

Glenn, FA chairman Greg Clarke and their counterparts at the SFA have previously said they do not think wearing a poppy to commemorate those who have died in armed conflicts is a political message, and have said the 2011 compromise agreed with the previous leadership at FIFA should apply.

Press Association Sport, however, understands that new FIFA president Gianni Infantino and Samoura believe that decision was a mistake and find it hard to understand why the home nations cannot see that this might create a precedent for other nations to break the rules as they see fit.

The first stage in any disciplinary process that might follow Friday's game would be for FIFA's match commissioner at Wembley to include the armbands in their report - given the enormous publicity this saga has attracted, including an intervention from Prime Minister Theresa May, it is very hard to see how this will not happen.

The case would then go to FIFA's disciplinary committee, which would announce its decision a few weeks later. 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.

But Glenn, a former Leicester director and food industry executive, certainly seems in the mood to fight as a matter of principle.

And England's players appear to agree with him, as Jordan Henderson said: "I think that it's very important for the country, for the players, to remember what those people have done for this country and (what they) sacrificed.

"I think that's really important for this fixture as well."

Glenn also revealed that the FA's financial strength - its revenues are forecast to grow by 35 per cent to £420million in 2018 - means it does not depend on FIFA to the same extent as most other member associations.

"We don't need FIFA's money," he said. "That probably allows us to be a bit more principled - they might see it as aloof."

But despite this apparent impasse, Glenn claimed he was still " optimistic about the new FIFA" and said he was "supportive" of the direction Infantino and Samoura were trying to take the scandal-hit organisation.

"Poppies haven't destroyed that relationship," he added.

Although there will be no poppy on the Northern Ireland players' black armbands, there will still be a minute's silence at Windsor Park on Friday night, while a card motif featuring a poppy will also be displayed in the West Stand along with other Armistice Day tributes.

Asked about the IFA's decision not to follow the FA and SFA's lead on poppies, manager Michael O'Neill said: "I have a lot of influence, none of it exists at FIFA.

"This is a decision that is made by FIFA, I think the association have done everything in their power to mark the occasion with the utmost respect, we will do that as a group as well.

"We didn't feel it was the right thing as an association to violate the regulation. As a group of players and as a management team we're happy that the decision's been made and we can focus on the football now."