A quarter of the League One and Two clubs that played in the Checkatrade Trophy's group stage have been fined by the English Football League for fielding weakened teams.
The competition was controversially revamped this season to include 16 invited under-21 teams from the Championship and Premier League. These sides, which could finish with as many as eight over-21 players on the field by the end of the game, were added to the 48 League One and Two teams to make 16 groups of four.
While the invited teams were encouraged to experiment with youth, the EFL teams had to meet "full strength" criteria that meant five of their starting line-ups had to have started the previous or following game, or have five of the 11 players who have made the most starting appearances in league or cup fixtures this season.
None of the invited clubs failed to comply with the requirement to start six under-21s but 12 EFL clubs broke the full-strength rules.
Luton and Portsmouth did so in all three of their games and have been fined £5,000 a match, and Fleetwood have been given a single £5,000 fine.
Bradford, Blackpool, Bristol Rovers, Milton Keynes Dons, Millwall, Charlton, Peterborough, Sheffield United and Southend have all been fined £3,000 each to bring the total to £62,000 in penalties. All 12 clubs have the right to appeal to the EFL board.
An EFL statement said: "All of the offences punished were due to a failure to meet competition rule 7.3 of fielding a full-strength team in and during all matches.
"The EFL did take into account a number of mitigating factors and also considered transgressions that were not within the spirit of the rules."
This last point refers to clubs who tried to circumvent the rules by substituting players within minutes of the games starting.
Luton, who advanced to next month's second round thanks to wins over Gillingham and West Brom's under-21 team, responded to news of their £15,000 fine with a statement on their website.
It said the League Two team was "dismayed" at the EFL ruling, which means they will now lose most of their £20,000 in prize money.
Luton chief executive Gary Sweet said: "We entered those teams with our eyes wide open and we accept that we would be fined for doing so. While we don't feel we should be paying 'fees' to get our youngsters experience, we view that as an investment in their development.
"We are staggered, however, that we have been fined the maximum amount for our first offence, which was winning away from home at a club from the division above with half-a-dozen first-team regulars in their team.
"We played nine graduates of our academy in that game at Gillingham, and seven against a West Brom side containing four players, two of whom who were internationals and had been transferred for several million pounds, and still beat both."
Sweet added that he believed their decision to play youngsters had "added value" to a dying competition and was the reason they attracted a good attendance for their final game against Millwall.
"We acknowledge our breach of the competition rules, but does our 'offence' make a mockery of the competition any more than a club substituting their first-choice goalkeeper after just a couple of minutes of the game to ensure they met the five-player starting rule?" said Sweet referring to Bradford's move in their game against Bury.