Allan Johnston, the Kilmarnock manager, is expected to be dismissed tomorrow morning after the club's board met to discuss his astonishing outburst from earlier today.

Moments before a scheduled press briefing Johnston revealed he would quit the club in the summer, suggesting that the deadline day decision of chairman Michael Johnston to sell teenage striker Robbie Muirhead to Dundee United was a major factor. It is understood the manager hadn't even informed his players of his decision before he made it public.

The club's board - itself in a state of transition - convened tonight to discuss its next move in the wake of the startling events. Johnston is to be succeeded by current director Jim Mann as chairman at the club's annual meeting on March 26.

Manager Johnston, who has been the subject of supporters' anger in recent times, was dismayed by the sale of Muirhead. With Michael Ngoo ruled out for the rest of the campaign and Lee Miller still struggling with a knee complaint, Killie, sitting in eighth place in the Scottish Premiership, have only one recognised striker - Josh Magennis - available for tomorrow's trip to Hamilton.

"I made my mind up before I came in," said Johnston. "There is a new chairman (Mann) coming in and I think it is important that there is a freshness about the club and it is time to move on anyway. Until then I will give 110 per cent.

"There are a number of things but that (Robbie leaving) certainly doesn't make your job any easier. I never found out Robbie was away until five past 12 on deadline day. Stuff like that, it is not the way things are done. It was very disappointing. Especially when you see a lack of goals this season.

"I spoke to the chairman and told him that if Robbie left we would only have one fit striker because Michael Ngoo is out for the rest of the season and Lee Miller is a few weeks away. I said that we definitely needed to bring another striker in to strengthen the squad. He said that even if Robbie left then we were not in a position to do that. You can see why the club had let him go with only a few months left of his contract.

"But the frustrating part was we didn't have the chance to strengthen the team, even though we had targets set up. It was really difficult to arrive at the decision to leave.

"It is not something you want to do. I trust in the players I have got but at the end of the day I think it is the best decision for myself and the club.

"It is disappointing but there is still a job to be done before now and the end of the season."

Johnston stressed the decision to sell Muirhead without bringing in a replacement was not "not a gamble (he) would like to take" at a club sitting 10 points ahead of Motherwell, who are in the relegation play-off spot.

The former Queen of the South boss said: "I don't think we can afford to. You can see every club strengthening. I think it was important to bring in a couple of players so that we are challenging up near the top.

"It is a difficult situation for the club. We obviously would have loved to keep Robbie but it was out my hands. We are still speaking to the board to see if we can come up with a wee bit of money to try to bring someone in, who has had their contract terminated.

"I don't think it will affect the players for Saturday's game. I am still confident in the players we have in the club. The players are desperate to put a run together. They want to be challenging for the top six."