The offending shirt was worn as part of a sponsorship deal with Paddy Power.

The bookmaker's name was displayed in a sash across the club's shirt in a pre-season friendly at Rochdale, with the FA charging Huddersfield last month.

The shirt was a spoof, with the deal actually seeing the club remove the sponsor from the front of their kit.

Huddersfield admitted the charge and were also warned about their future conduct by an independent regulatory commission.

The slogan on the Championship side's shirt broke FA regulation C.2(i), which states advertising should consist of one single area on the front of the shirt, not exceeding 250 square centimetres.

Paddy Power issued a statement in which it compared the £50,000 fine to the £10,000 fine given to Millwall over alleged racist chanting by fans in an FA Cup match against Everton in January.

The bookmaker did not respond to other questions about the sponsorship.

Club asked referee to ban kit

In the FA's written reasons Martin Coy - who refereed the friendly on 17 July - said Huddersfield chairman Phil Hodgkinson had asked him to ban them from wearing the kit before the match.

"He said that my decision could then potentially be good publicity and part of the advertising campaign," Coy said in a witness statement.

"I was uncomfortable with this and felt it was not my place to ban the kit outright, but I informed them that I would recommend they followed the rules and advice from The FA."

Coy was then told Huddersfield would not wear the shirt, details of which the club's operations manager Ann Hough said were kept from the Terriers board until the day of the game.

The FA warned the club on the same day that they may take action if the shirt was worn, but Hodgkinson said the sponsor threatened legal action if they did not wear it.

"The sponsor said that it would be deemed to be a material breach of the sponsorship agreement if the team did not wear the oversized logo," he said.

"In the circumstances, when faced with the threat of serious legal action from the club's main sponsor, and with no time to seek external legal advice, we felt we had no alternative but to wear the oversized logo in the match."

'Huddersfield motives were financial'

Huddersfield said they did not think the FA's kit regulations applied to friendlies, but the commission said it was a "blatant disregard" of the rules.

"The club's motives were financial, deliberately running the risk of being 'charged'," it said.

"The decision not to wear the sash shirt was one the club should have made; it should not have tried to hide behind the referee.

"Involving the referee in that way was wrong and also not an insignificant aggravating factor. The referee displayed commendable judgment in the face of such conduct."

The FA told the panel: "The decision to enlarge the advertisement in such an overt manner was irresponsible, particularly in the current climate regarding gambling."

The one-off shirts were subsequently auctioned, raising more than £30,000 for charity.

Paddy Power have agreed similar deals to 'unsponsor' the shirts of Newport County, Motherwell, Macclesfield Town and Southend United.