It is understood Smith made the decision mainly for personal reasons and felt the time was right to step down following an eventful period in a role which has always attracted criticism no matter the identity of the incumbent.

The SFA gave little away in a brief statement but there may be more clarity tomorrow once the formalities of the resignation process are resolved.

The 55-year-old came into the role in June 2007 with a well-established profile in the game as a successful player with the likes of Rangers and Brighton and latterly his role as media pundit and players' agent.

His resignation came amid calls from Livingston for an investigation into Smith's conduct over a disciplinary case against striker Robbie Winters, and days before former Scottish First Minister Henry McLeish is expected to publish his wide-ranging review of the Scottish game.

The news also came shortly after Smith announced a review of the SFA player appeals process, which had attracted recent criticism from Rangers and Celtic among others.

The SFA statement read: "The Scottish FA can confirm that Gordon Smith has resigned from his post as chief executive. A further statement will be issued tomorrow."

The appointment of Smith, who moved into accountancy after a short spell as St Mirren assistant manager, was generally welcomed in the game as a positive step given that he was a "football man".

But his background failed to shield him from criticism over issues such as George Burley's disappointing reign as Scotland manager and the fixtures for the recent World Cup qualifying campaign, which kicked off in the searing heat of Macedonia.

Smith's bid to bring in retrospective punishment against diving and cheating was foiled by FIFA's reluctance to undermine the authority of the referee.

And his attempts to move towards a pyramid structure for domestic football have yet to come to fruition despite years of talks with the myriad of governing bodies.

However, he was praised for employing Craig Levein as Scotland manager in December despite well-publicised previous friction between the pair, although Smith denied any personal issues.

And he was proud of the SFA's achievements in youth football during his reign, such as the scheme to introduce thousands of schoolchildren to organised football.

But only last week Smith faced angry protests from Livingston chairman Gordon McDougall over the disciplinary case against Winters.

McDougall wrote to SFA president George Peat demanding an investigation into Smith's alleged involvement in accusations Winters had dived in an Irn-Bru Third Division game against East Stirlingshire in February, a game attended by Smith.

The SFA disciplinary committee last week threw out the case against Winters over claims he got Michael Bolochoweckyj sent off, but McDougall claimed Smith asked for a DVD of the match from home manager Jim McInally and accused him of overstepping his authority.

Rangers boss Walter Smith described the news as "regrettable" given Smith's football background had made him a popular appointment.

Former Scotland boss Craig Brown was "astonished" by Smith's departure after feeling he had settled in well to the post, while Smith's Scottish Premier League counterpart, Neil Doncaster, was "flabbergasted".

Walter Smith had high hopes for his namesake when he took over the governing body in June 2007 but admitted the expected results were not always forthcoming given the competing interests in the game.

The former Scotland manager said: "I know Gordon and I know he is very passionate about his football and he'll have his own ideas.

"I don't know the circumstances which have forced him to make that decision. From my own point of view, it's a regrettable one because he's a football person and he was placed in a position where we would have hoped he could have influenced a lot of things.

"Unfortunately, that doesn't seem to be the case."

The Ibrox boss refused to give his opinions on Smith's successor.

"It's hard enough trying to win a league without picking the chief executive of the SFA," he said.

"That's not something that's in my remit. I think Gordon himself would look upon it and say he was up for the challenge, he was a football person and we were all pleased that he had the opportunity to do so."

Another former Scotland boss, Brown, had also been encouraged by the appointment.

The Motherwell boss told BBC Scotland: "I'm astonished, actually. I thought he was settling in well.

"It's a very difficult job. I was 16 years working at the SFA, I worked under three different chief executives.

"They all had their qualities but I thought Gordon was an inspired appointment and I still think that, given time, he would have got things going.

"The wheels turn very slowly at the Scottish Football Association because of the committee structure and it must be frustrating for a guy who's full of initiative."

Doncaster added: "I've heard the news a few minutes ago and I am absolutely flabbergasted. I didn't see that coming at all.

"I would like to wish Gordon well for the future. Since I arrived last summer I have really tried to build relationships between the SFA, the SFL and ourselves. That will continue going forward."