The referee Dougie McDonald has escaped with a warning from the Scottish Football Association despite being found economical with the truth over the reversal of a penalty award to Celtic earlier this month.

The Parkhead side wrote to the Scottish FA for clarification after the decision to hand them a penalty at Dundee United was reversed. At the time it appeared McDonald's change of heart was prompted by the assistant referee Steven Craven, which was what McDonald told the refereeing observer.

Craven resigned over the abuse he suffered in the wake of the incident. It has now been confirmed McDonald made up his own mind. "What he [McDonald] said wasn't the correct information, you can call it a lie if you wish," Stewart Regan, the SFA's chief executive, said. "The view of our committee was that he acted in the spur of the moment, he said something that he fully regretted.

"Dougie said things in the heat of the moment, they weren't true. He said things in the heat of the moment which he regrets entirely because they didn't fully explain the process involved." McDonald did not respond to attempts by the Guardian to contact him tonight.

Regan said Craven's resignation was down to a number of reasons, including that "his role was not fully articulated in the post-match reports. That was one of the concerns Steven had, that his role had not been fully communicated."

In defending the light punishment handed down to McDonald, Regan said: "Dougie made the correct decision [not to award the penalty]. The correct decision is what happened here. Dougie has apologised to everybody; to Steven and the SFA. He is full of remorse."

Celtic are unlikely to be placated by the turn of events, not least because it contained an admission that McDonald had been economical with the truth. Regan denied, though, that there was any bias against one club.

"Absolutely not," the chief executive said. "I categorically deny any suggestion of that whatsoever. Any suggestion of bias is totally unfounded." Celtic said there will be "no comment at this stage" from the club.