Underperforming schools need to work a lot harder to boost their performance or face drastic consequences, prime minister David Cameron has warned.

In a speech, he said that headteachers failing to deliver a high standard of education will have to justify their positions as school leaders. If they are found to be lacking in authority, they run the risk of being sacked.

Mr Cameron declared that if the Conservatives win the General Election in May, one of the key objectives of the new government will be "an all-out war on mediocrity" within education.

"No-one wants their child to go to a failing school and no-one wants to them to go to a coasting school either," the prime minister said.

"'Just enough' is not good enough. That means no more sink schools and no more 'bog standard' schools either. Our aim is this: the best start in life for every child, wherever they're from - no excuses."

Dr Mary Bousted, general secretary of the Association of Teachers and Lecturers, rejected the core of Mr Cameron's arguments, explaining that his criticism of schools is "self-serving, publicity-seeking nonsense".

Her comments come on the back of her expressing disapproval over new school league table data that suggests double the number of secondary schools in England are failing to meet performance criteria set out by the government.

"Performance tables are too crude a measure of how well a school or college performs and with such major reforms to the exams system over the last year, it is impossible to compare results from previous years," she said at the end of January.

According to the BBC, schools that are identified as being in need of development will automatically be considered for academy status. This strategy, however, is not unanimously backed.

Alasdair Smith, national secretary of the Anti Academies Alliance, told BBC Radio 4's Today programme that it is far too simplistic to assume that transforming a school into an academy will deliver better quality education.

"There is not a single scrap of evidence that academy status improves our education system and increasingly there is plenty of evidence that it is producing a chaotic education system," he said during an interview.