Motherwell midfielder Steve Jennings has denied any wrongdoing as investigations continue into betting patterns surrounding his red card against Hearts. The Association of British Bookmakers reported unusual bets being placed on the prospect of a sending-off in Tuesday's Clydesdale Bank Premier League game.
The ABB reported their findings to the Scottish Football Association and the Gambling Commission.
It is unclear how many bets were placed but the ABB said on Thursday that two of their members had sparked the alert, including Blue Square.
Blue Square later revealed that only one customer had aroused their suspicion.
Spokesman Alan Alger told BBC Scotland: "At 2pm on the day of the game we had a new account opened that was planning to back a red card for Motherwell at 10-1.
"That new account tried to place as much as the account would allow but we've got certain measures in place that stop duplicate bets and bets of a certain amount on certain markets.
"That person did return and tried to then place another £100 at 10-1 and consistently in the lead-up to kick-off tried to get as much money as possible through that account on that particular bet, but those fail-safes at our end stopped that.
"The customer stood to win £2,000 from a Motherwell red card. We're withholding that pending investigation."
He added: "We did take other bets on a Motherwell red card as we would expect to do in minimal amounts on any market, especially on live (TV) games.
"None of the other bets were particularly suspicious, they were all at lower amounts on that particular selection."
Blue Square would not reveal where the bet was placed but the spokesman hinted it was the area revealed in other reports, namely Liverpool.
However, he cast doubt on information previously given unofficially from within the betting industry that £500 was wagered on Merseyside.
"This may be a red herring because I think we were the only ones offering 10-1 and we certainly didn't see £500 attempted," Alger said.
"That's not to say that specific bet hasn't been reported to the ABB."
Jennings has been told not to speak publicly by his employers but he is understood to have categorically denied any wrongdoing.