Secondary teachers have warned ministers and curriculum planners to inject resources and materials into Higher Still reforms or face a union backlash. Union leaders insist it is “crunch time”.

David Eaglesham, the SSTA general secretary, told his union’s conference in Dundee last weekend: “If they do not address these issues, there is going to be a real crisis. We have come to the point where we have to speak out very clearly. The implementation date is less than a year away.”

There was unanimous support for a consultative ballot on boycotting the post-16 reforms if five key conditions are not met.

At its conference next month in Dundee the Educational Institute of Scotland will face calls for outright opposition to Higher Still - an appeal union leaders accept could gain the support of the membership.

Peter Wright, West Lothian, proposing the ballot, told SSTA delegates Higher Still was the most significant education reform for a generation. “It’s a reform we cannot afford to get wrong. The ballot will act as a spur to ministers and the Higher Still Development Unit to ensure they get it right - and on time.”

Mr Wright wants assurances on teaching time, bi-level teaching, the balance of internal assessment, the number of testing items in the national assessment bank and additional cash for new courses.

Bill Walker, Highland, and a member of the national Higher Still implementation committee, said: “It’s very near to crunch time for Higher Still. For four years now it’s been a great leap of faith.”

Earlier Philip Banks, chief inspector, told conference Higher Still was not “a juggernaut waiting to crush teachers under its wheels. It will be a controlled and gradual approach and I expect to see schools building up year by year on a solid platform.”

Mr Banks, seeking to calm fears, said the reforms had taken on board the views of teachers at every stage. After concerns about English and Communications, performance criteria were simplified and the amount of assessment cut by 25 per cent, he said.