The announcement was made at a Monday media conference held 24 hours after BBC Scotland disclosed that Thompson had decided a change was necessary at the top.

And Falkirk boss Ian McCall and Inverness Caledonian Thistle manager Steve Paterson have emerged as favourites to be Smith's successor.

Thompson hopes to make an appointment within days and says the new manager will be someone presently working in Scottish football.

That rules out former Dundee United and Scotland defender Richard Gough and his former boss at Rangers, Walter Smith.

"There's no question that this has been pretty tough decision, but I've been watching what the club has been doing and how the manager has been doing and formulating my own ideas for some time," he said.

"I stated that if we didn't start picking up the points then action would be taken.

"The Premier League table doesn't lie. I said I would judge it on performances and see how results went.

"The manager has been with us two and a quarter years and during that time I can't remember missing two games."

Former Aberdeen boss Paul Hegarty has been appointed interim manager, while the future of coach Maurice Malpas will be the subject of further talks.

Newspaper reports have already suggested that McCall has been approached to take over from Smith.

Thompson insists that nobody from United has talked with the former Bradford, Dunfermline and Rangers winger.

But the new United chairman is known to have a preference for a "younger, hungrier man" to take over from seasoned campaigner Smith.

Smith led unfashionable St Mirren to the Scottish Cup before heading for Aberdeen, where many believe he was unfairly dismissed for not being able to match the record of Sir Alex Ferguson.

But Smith's record of 31 wins in 99 matches since moving to Tannadice does not make impressive reading.

While some on the board may wish to turn to former United defender Walter Smith, who has since gone on to manage Rangers and Everton, such an appointment is unlikely.