Gordon Strachan resigned as Celtic manager on Monday 24 hours after his team's failure to retain the Scottish Premier League title.

Strachan's side finished second behind Glasgow rivals Rangers for the first time in four years following Sunday's 0-0 draw with Hearts at Parkhead.

The former Scotland international is believed to have grown tired of criticism from a section of the club's fans and a lack of backing from the board in the transfer market.

Strachan, who won three titles and three domestic cups in his four years in charge, is reported to be considering a move to Sunderland, whose manager Ricky Sbragia stepped down on Sunday.

Celtic confirmed Strachan's departure on their website and Strachan said: "I have enjoyed my time immensely at Celtic and clearly I will be sad to leave this great club."

Strachan had refused to discuss his future immediately after the Hearts match, but, despite his success in Europe, where he twice led Celtic into the last 16 of the Champions League, the Parkhead faithful never took him to their hearts in the way they did his predecessor Martin O'Neill - who took them to a UEFA Cup final.

A season of failure by Celtic's standards appears to have been the final straw for Strachan.

"We have done all we can to bring success to the club and we were delighted to deliver three SPL titles, other domestic silverware, as well as making some great progress in Europe," he said.

"It is just disappointing that we did not manage the fourth championship. However, the players can hold their heads high in terms of what they have done for the club in recent years.

"I would like to thank the Celtic board for all the support they have given me during the past four years, in particular Dermot Desmond, John Reid, Peter Lawwell and former chairman Brian Quinn - I could not have asked for any more support.

"I thank the fans too for the tremendous support which they have given both myself and the players. I wish Celtic and our supporters nothing but success for the future."

Celtic chief executive Lawwell paid tribute to the former Southampton and Coventry boss's achievements at Parkhead.

"Gordon has given everything to the club and worked tirelessly to bring success to Celtic," Lawwell said. "He has achieved so much at both domestic and European levels.

"It has been a pleasure to work closely with Gordon and he leaves the club with all our best wishes.

"We thank Gordon for his commitment and achievements at the club and we also thank our fans for backing us all the way this season.

"Our fans know how to support their club and we will be doing all we can to once again bring back the title to Celtic Park, something which our support deserves."