Secondary teachers remain "extremely anxious" about their workloads as the latest changes to the curriculum are introduced in schools, MSPs have been told.

Teaching unions said surveys showed that stress levels remain an issue while there is little change in confidence about the amount of support being offered to implement the new Higher exams.

Holyrood's Education Committee heard that the workload faced by teachers to prepare pupils for the national qualifications which were sat in August this year was "unsustainable".

The unions called for greater levels of support as the next phase of the Curriculum for Excellence (CfE) - the new higher - is taken forward in the coming school year.

During a committee evidence session, Terry Lanagan, of the Association of Directors of Education in Scotland, told MSPs that the implementation of the national qualifications, which replaced standard grades, was always going to a "key pressure point" for the teaching profession.

Referring to the high pass rates seen in August, he added: "I think it is to everyone's credit that the first set of national qualifications and the first set of exams went so smoothly."

Ken Muir, chief executive of the General Teaching Council for Scotland, added: "We are very much over the hump in terms of getting CfE into place".

But Larry Flanagan, education convener of teaching union the Educational Institute of Scotland, said: "An assessment of last year has to acknowledge that the workload burden that was faced by teachers in schools is simply unsustainable."

He said a survey of 7,000 teachers had revealed that more than 80% thought their workload was a severe cause of stress.

Another more recent survey, which asked if action had been taken within schools to reduce workload in the coming year, showed that 80% said no action had been taken.

Mr Flanagan said that 65% of teachers rated the support available for implementation of the new CfE Higher as "poor".

"We think in terms of moving forward we have to recognise that as an exceptional effort to deliver the qualifications, but it does need to be addressed," he said.

"We seem to be getting a repeat of last year and we said this was unsustainable."

Jane Peckham, Scotland organiser of the National Association of Schoolmasters Union of Women Teachers, echoed Mr Flanagan's concerns.

"I wouldn't agree that we are as far up and over the hump as we should be," she said.

"In terms of workload - I think teachers still feel extremely anxious about the next phase. It would be foolish to think we are over the worst."

Richard Goring, professional officer of the Scottish Secondary Teachers' Association, told the committee that many teachers were working 50-60 hour weeks to keep up, with many feeling "totally submerged by the whole thing".

He said: "Our surveys showed very little change in being confident with both Education Scotland and Scottish Qualifications Authority in terms of the support that is available this year compared to last year."

This view was countered by the SQA and Education Scotland, with both organisations insisting there has been unprecedented support for staff.

Mr Lanagan said: "I am quite clear, with 37 years working in education, that there has been no initiative in Scottish education during that time where there has been more communication or more support."

Dr Janet Brown, chief executive of the SQA, said: "I think we have provided very good support. I think the challenge is to make sure people can access it, use it, and people can ask questions, that there is communication."

Mr Flanagan said: "Proportionately I would say this is not being resourced to the kind of accolade that we have been hearing.

"The single biggest resource that has been missing is time for teachers to actually assimilate that material and have that professional dialogue around implementation."