Grimsby Town have accepted a suspended fine after breaches of the English Football League’s Covid-19 rules led to three matches being postponed.
It is thought they are the first club in the country to be sanctioned for breaking the rules during the pandemic.
The postponements in September followed a positive test for player Jack Curran.
But an investigation found that social distancing rules had not been followed, meaning more players than should have been necessary had to self-isolate.
Players were allowed to congregate in communal areas at their Cheapside training ground, while the BBC also understands former boss Ian Holloway admitted to investigators that he played darts with some of his players, which he claimed was a training tool.
It is thought players were also involved in car sharing and that the Mariners failed to conduct an adequate risk assessment by a suitable specialist before re-opening their kitchen at the training ground.
Although players and staff were told to self-isolate for 14 days – leading to the postponements – the investigator found that, if protocols had been properly observed, only two players should have been affected.
“Quite honestly this should not have happened,” chairman Philip Day told BBC Radio Humberside after the club were fined £4,880, which is suspended until June.
“We’re disappointed because, prior to the players returning to training, we had put in place protocols which were approved by the EFL and we gave a full morning’s training to the staff and players to ensure they were fully conversant with the protocol.
“The protocols are there for a purpose and they must be complied with. They’re all adults, but sometimes you’ve just got to reinforce the message time and again.”
Day also said the playing of darts was “unknown to the board and senior management” and was “really beyond the protocols”.
“Olly [Holloway] used the playing of darts to build up team ethos and sadly he shouldn’t have done it,” he added.
Grimsby are also facing other costs, including an EFL bill of £13,000, believed to be the cost of the investigation, and reasonable costs incurred by the teams they were due to face at the time – Cheltenham Town, Bradford City and Hull City.