John Hartson was once on the end of a major Hampden injustice while playing for Celtic - but he cannot see any point in his old club writing to the Scottish Football Association over the latest controversy at the national stadium. Celtic issued a statement on Monday evening revealing they were 'seeking an understanding' of the failure to penalise Inverness defender Josh Meekings for stopping a goal-bound Leigh Griffiths header with his hand. Celtic were leading 1-0 at the time but went on to lose 3-2 and some fans have questioned how referee Steven McLean and additional assistant Alan Muir could have missed the infringement. Celtic striker Leigh Griffiths has a goal-bound shot blocked by the outstretched arm of Josh Meekings . Kris Commons of Celtic appeals unsuccessfully for a penalty before Celtic crash out . John Hartson, pictured at golf charity event, has urged his former club to move on from the injustice . Hartson had a goal wrongly disallowed for offside while Celtic were 2-1 down in an Old Firm League Cup final and the Welshman went on to miss a last-minute penalty that could have sparked extra-time. But he refused to dwell on the match officials' error - and called on Celtic to move on from the latest setback rather than writing letters. 'I'm not sure what sort of purpose it's going to serve,' said Hartson as he launched a 'Know Your Balls' testicular cancer awareness drive at his charity's annual golf day at Mar Hall in Bishopton. 'It has happened before and will happen again. There's a lot of disappointment at Celtic and rightly so, it should have been a penalty. David Raven (2nd right) celebrates with team-mates after scoring the late winner in 3-2 victory . Celtic pair Aleksandar Tonev (left) and John Guidetti look dejected as their hopes of a domestic treble end . 'I think the referee just missed it. When you are questioning people's integrity and honesty, that can sometimes go a little overboard. The referee just missed a decision, I'm sure if he'd seen it he would have given it. 'It happened to me in 2003 when I scored a legitimate goal against Rangers at Hampden Park in a cup final. It was proven to be two yards onside and it got called offside. It was a big moment for me. 'I was disappointed for two days and I got over it, and I think Celtic will get over it. 'They feel they have a right to complain, and that's what they want to do, but I'm not too sure what they are going to gain by it.' Hartson believes Ronny Deila can still class his first season as Celtic manager a success if they go on to clinch the Scottish Premiership title - they can move eight points clear of Aberdeen by beating Dundee at Dens Park on Wednesday. 'I think they will never get a better opportunity to win the treble,' the former Wales striker said. 'They got the League Cup final in the bag and they could have played a Championship team (Falkirk) in the final. Celtic manager Ronny Deila has criticised an official's decisions during Scottish Cup defeat to Inverness . 'So it's a missed opportunity but I think if you had offered a chance to win a double to a young rookie manager who had not managed anywhere near this level, a lot of people didn't know who he was, I think he would have taken that. 'When he sits in the summer and has a moment to himself he will probably realise it has been a successful season, tinged with disappointment because he has not joined great managers like Jock Stein and Martin O'Neill. 'Obviously they have a little work to do to get over the line but they should win the league and they should be fairly pleased.'
Celtic were defeated 3-2 after extra-time in the Scottish Cup semi-final .
Leigh Griffiths had a goal-bound shot blocked by a clear handball .
However, no action was taken against offender Josh Meekings .
The Hoops have written the SFA for an 'understanding' of the decision .