Neil Lennon last night revealed how he agonised over his decision to leave Celtic at the end of the season, as Sunderland emerged to head a list of potential destinations for the Parkhead captain.

Lennon has opted against seeking a further 12-month contract at the Bank of Scotland Premierleague champions and feels he has picked the perfect time to depart after seven successful years.

Gordon Strachan, the club's manager, paid tribute to "a great captain and friend", while Peter Lawwell, Celtic's chief executive, said Lennon would be remembered as one "of the club's finest servants".

"Obviously, having been with the club for so long, it will be a real wrench to leave," said Lennon, "but I have thought long and hard about this decision and believe that it is the right one.

"I feel it is right to go out on a high and, given that we have just secured the league title for the second year running, I believe that this is the best decision at the best time."

Lennon's resolution to leave is certain to be of interest to Roy Keane. The Sunderland manager, a Parkhead team-mate last season, failed in a speculative approach to lure the 35-year-old midfielder last August.

It is believed Keane remains keen on adding Lennon to his squad, possibly with a coaching role as part of any agreement. Sunderland are on the brink of promotion to the Barclays Premiership, yet Keane will be given upwards of £10m to invest in his squad even if they remain in the Coca-Cola Championship next season.

The Herald also understands that Pearse Flynn, the Livingston chairman, spoke informally with Lennon on Monday to ascertain his situation as the first division club continue their hunt for a new management team.

The feeling at Almondvale, though, is that they have little chance of luring the former Leicester City player who is likely to have far more lucrative options available at a higher level in England. Martin Reilly and Mark Donaghy, Lennon's representatives, will gauge interest over the coming weeks but, for now, their client's focus remains on completing his Celtic career with a flourish.

The Parkhead side will be presented with the SPL trophy after Sunday's home match with Hearts, with the Tennent's Scottish Cup final against Dunfermline on May 26 providing a showpiece event for Lennon's last appearance.

"I have enjoyed my time at the club immensely," Lennon said. "I have worked with two fantastic managers in Gordon Strachan and Martin O'Neill, enjoyed working with some quality players and had a great relationship with the Celtic board and all the staff. I have also enjoyed a good relationship with the supporters and sincerely appreciate the backing which they have given me over a number of years.

"This season has been particularly pleasing, having won the championship, making the Scottish Cup final and getting to the last 16 in the Champions League."

Lennon was made captain by Strachan after the departure of Jackie McNamara to Wolves two years ago. "It was a boyhood dream to play for the club I loved," added Lennon. "I am very proud to have achieved this and played for Celtic for so many years and when Gordon Strachan made me captain I was, of course, honoured.

"I look forward to joining my team-mates and the manager in lifting the SPL trophy on Sunday. Great credit should go to the manager and his staff for all they have done over the past two years.

"We still have a good bit to do before the end of the season and I will be doing all I can to make sure we bring the Scottish Cup back to Celtic Park."

Strachan will step up his search for midfield reinforcement, with West Bromwich Albion's Jason Koumas the latest to be linked. The manager insisted Lennon's influence had been a crucial factor in him attaining success after taking over from O'Neill in the summer of 2005.

"Neil has been a tremendous asset to Celtic and a great help to me since I came to the club," said Strachan. "He is a true competitor and has always been a good team-mate, which I'm sure every player here now, or who has played alongside him in the past, would confirm.

"We respect his decision and I understand fully that he feels the end of the season is the right time to leave. Neil is proud of his achievements at the club, and rightly so, and he is also proud to be captain of Celtic. I would like to thank Neil, on a personal level for being a great captain and, indeed, a friend, through some difficult moments."