The number of people in Scotland seeking academic help for primary and secondary school pupils has almost doubled in the past five years, a tuition company has said.

First Tutors, a UK private tuition service, said demand had risen by 91% and the increase was "in the thousands."

Kumon, another private tuition body, has reported a 40% rise in pupils across its centres in Scotland since 2011.

George Hawkins, the founder of private tuition body Step Ahead said many parents in Scotland have lost faith in state education.

John Swinney, the education minister, has faced criticism in recent weeks after the Programme for International Student Assessment (PISA) showed Scotland falling down league tables in reading, maths and science.

Mr Hawkins said: "Many parents realise that their children need extra help, irrespective of how able and caring a teacher might be....teachers in schools are up against it, there's too much paperwork, and successive governments keep tinkering with the system and changing the rules."

The 2015 Programme for International Student Assessment (Pisa) concluded that Scotland's performance was now "average" compared to other developed countries in all three disciplines.

In 2000, when Scotland first took part in the OECD survey of 15-year-olds, its performance in reading, science and maths were all above average.

Countries which have now moved ahead of Scotland in science include England, New Zealand, Slovenia, Switzerland and the Netherlands.

In reading, a greater number of countries performed significantly higher than Scotland with Australia, Germany, the Netherlands, New Zealand, Norway and Slovenia all moving ahead.

While performance in mathematics has not declined since 2012 it is still lower than it was in earlier years and the number of countries statistically above Scotland is the highest it has been since 2003.

The stark findings have thrown the spotlight on the implementation of the controversial Curriculum for Excellence (CfE) reforms which were introduced in 2010.

The changes were supposed to improve basic standards and empower teachers.