Teachers in Scotland spend 60% of their working hours in the classroom which is higher than their counterparts anywhere in the western world.
The figure came from a survey carried out by the Organisation for Economic Co-operation and Development (OECD).
It said teachers in Scotland had less time during the school day to mark children's work and prepare lessons.
The report comes as teaching unions are preparing to fight a possible freeze in pay in the next financial year.
Union leaders are also bracing themselves for a battle over the McCrone deal on working conditions which has been perceived as generous by council leaders.
The Educational Institute of Scotland suggested Scotland's largest council, Glasgow, was being unreasonable in trying to re-open the national pay and conditions deal to ensure teachers do more work once children have left the classroom.
--8 Sept,2010