Dundee United chairman Stephen Thompson has resigned from the board of the Scottish Premier League citing "professional differences".
The United chairman has announced the decision amid ongoing discussions for the reform of the Scottish game.
A statement on dundeeunitedfc.co.uk read: "Dundee United chairman Stephen Thompson has resigned from the SPL board with immediate effect, due to professional differences."
Following Thompson's departure, the SPL board is comprised of Ralph Topping (SPL chairman), Neil Doncaster (SPL chief executive), Eric Riley (Celtic), Duncan Fraser (Aberdeen) and Michael Johnston (Kilmarnock).
The move comes as SPL clubs prepare to meet next Monday to discuss reconstruction proposals. Earlier this month Doncaster revealed SPL clubs had "unanimously" agreed to seek the expansion of their membership.
The SPL chief executive revealed clubs were united in backing an idea which could see their ranks double to 24. The plans would see two leagues of 12 split into three divisions of eight after 22 games.
The plans would also mean the top eight teams play each other twice again for a 36-game season, two less than the current model, which splits into two after 33 games. The bottom four of the SPL1 would join the top four of SPL2 and complete their own extended play-off system, with the bottom eight teams of the 24 playing each other twice again.
The proposals are significantly different to those adopted by the 30 Scottish Football League clubs for a three-tier structure. The SFL plans are for a 16-10-16 structure with a number of promotion/relegation play-offs at the end of the regular season.
The SPL confirmed Thompson's departure in a statement on its website.
"The Scottish Premier League can confirm that Dundee United chairman Stephen Thompson has resigned from the SPL board with immediate effect," the statement read. "Stephen was appointed to the SPL board in September 2011 and we would like to thank him for his contribution as a director."