“I just think the problem lies at the start of the season,” said the former Celtic star. “They don’t get much time off in the summer because they are back early to get ready for the Champions League qualifiers.
“Having to play six games before they can even qualify is a huge demand and it’s unfair on countries like ours.
"There’s other countries won’t have started their pre-season training before our teams are playing in Europe.”
Celtic finished the 2014-15 season on May 24 when they defeated Inverness Caledonian Thistle 5-0 at Celtic Park in the Scottish Premiership.
The Bhoys’ 2015-16 campaign began on July 15 when they faced Stjarnan in the Champions League qualifying second round at home.
The Celtic players did not even get a two-month break, and perhaps this is a reason why they are not doing so well in Europe at the moment.
The Hoops failed to qualify for the group stage of the Champions League and are now in danger of getting knocked out of the Europa League at the group stage.
Ronny Deila’s side are fourth in Group A at the moment with just two points from four matches, three points behind second-place Fenerbahce.
Celtic are doing well in the Scottish Premiership, though, as they are as many as six points clear at the top of the table.