The chairman of the Rugby Park club has been under pressure from supporters and local businesses to cede control since sacking Kenny Shiels last month.
A group of companies who are keen to take the club out of Johnston's hands yesterday released a statement claiming that Johnston had asked for a seven-figure sum for the Ayrshire outfit, who have debts of almost £10m, despite having bought his stake for £1 in 2005, with predecessor Jamie Moffat then writing off half of a £1.8m loan to the club in 2010.
The Ayrshire Business Group released a statement through leader John Gall, managing director of Browning's the Bakers. It read: "One group member advised that Michael Johnston has formally intimated that a seven-figure sum, in addition to the settlement of Jamie Moffat's loan, is required for him to hand over control of the club.
"The group are astonished by Mr Johnston's valuation and shocked by his blatant profiteering. They have unanimously agreed any such investment would be better utilised directly in the club.
"The group reiterated their strong belief that Mr Johnston should only be entitled to the £1 he paid in 2005, and they reject the exorbitant price stated by Mr Johnston."
Johnston, the sole member of the club's board, rebutted the allegations. He said: "The statement from the group is wholly inaccurate. I have not made any proposal to anybody regarding the takeover of my shares or any loan to be repaid to Jamie Moffat. Following a meeting with Bill Costley [former chairman] last month, I told him I would be happy to meet with the Ayrshire group but I haven't heard from anyone."
The consortium of Ayrshire firms vowed to persevere in their bid to change the ownership.