The government's drive to improve test results for English and maths in primary schools is being hampered because many teachers are not up to the job, according to a new report by academics at the University of Toronto.

Although most teachers believe that they have mastered the government's literacy and numeracy strategies, the study concluded that many still lack sufficient understanding of English and maths, and of how to teach them, to make good progress with their pupils.

The report came as David Miliband said that bad teachers should "leave their posts with dignity".

"It is neither in pupils' interests nor in the longer term interests of staff that they struggle on for long stretches of time, failing to meet their responsibilities," he said.

The school standards minister also said that teachers' pay should be genuinely related to their performance.

"I believe it is unfair when outstanding performance is not rewarded. Teachers are human - and pay, in our culture, is the most visible and acceptable sign of recognition for most people", he said.