The principal of a Norfolk academy has hit back at claims their increase is creating a two-tier education system.

Teaching unions the National Union of Teachers (NUT) and NASUWT held their annual conferences over the bank holiday weekend where the rise of academies was criticised.

Representatives warned that academies and free schools, which do not have formal links to local authorities, will break up the traditional state school system and become a form of back-door privatisation.

In Norfolk, several schools have taken the academy route, while a free school opened in Norwich last year, with several more due to open over the next 12 months. However, Rachel de Souza, principal of Ormiston Victory Academy in Costessey, said that sponsored academies, where local organisations get involved in the running, gave schools a 'fresh start'.

The school was in special measures for three years, but after a year of transformation, it became one of the most improved schools in the country.

It saw a 27pc improvement in the number of students getting five A*-C grades at GCSE including English and maths last year and Mrs de Souza said that they had set themselves high targets to achieve this year.

She said that since the academy forged links with the Norfolk and Norwich University hospital, the students have benefited from work experience with dental and cosmetic surgeons and talks from industry leaders.

Mrs de Souza said working with the local community was one reason why the academy had enjoyed success.

She added: 'It's a whole community effort - parents, students and local businesses. I think the academy movement has been a huge force for good. If you look at Norfolk, the sponsored academies have proven to be a great turnaround for schools that were not providing an acceptable level of education.'

Responding to claims the status has forced schools to become more competitive, Mrs de Souza said academies were working together, rather than against each other, with a 'strong collaborative approach'.

However, Colin Collis Norfolk branch secretary for the NASUWT union, said: 'Over time, because of the way academies have been set up, we will end up with a range of organisations supporting academies. There are chains developing.

'My concern is that this will make the delivery of state education worse. It's a big mistake to focus on this structure - it will not improve the education standard in this country. We will regret it in the long term.

'What's already starting to happen is instead of schools cooperating together we are getting competition between them,' he said. 'People will be looking to make a profit from education and we think that the public service ethos is considerably at risk.'

Currently 1,641 out of 3,261 secondary schools in the country are academies or in the process of becoming one.