Increasing numbers of incompetent teachers could be banned from the classroom under a new system for identifying substandard staff.
Meanwhile, an investigation has been launched to find out why so few underperforming teachers are being referred to the General Teaching Council for England, which has the power to remove them from the teaching register.
Just 10 teachers have been struck off for incompetence since the council was set up in June 2001, The TES can disclose. There are almost 500,000 teachers in the system.
Most local authorities have not referred a single teacher suspected of not being up to the job.
Keith Bartley, chief executive of the council, said the system for passing on concerns about weak teachers was "virtually non-existent" in many authorities.
"I am hopeful that we can now address the issue in underperformance," he said. "I could not begin to say how huge the problem is.
"I don't think we are talking about a broken workforce. It's the best qualified it's ever been, and probably the best trained in terms of initial training. But the issue for us is whether all children can be assured that the teacher in front of them is competent."
The GTC, with the Department for Children, Schools and Families, has begun research into the system for referring substandard teachers to discover why the numbers remain persistently low. Results are expected later this year.
In cases in which a teacher is dismissed for incompetence or resigns when dismissal is likely, employers are supposed to inform the council. But it is feared incompetent teachers are being recycled among other schools rather than removed from the profession.
The council has held just 64 competency hearings from 155 referrals in the past seven-and-a-half years. In 13 cases, it was decided there was no case to answer and the teacher was allowed to return to work.
Mr Bartley said there was a distinction between incompetence and poor performance that could be difficult for schools to address. A much higher number - 682 to the end of 2008 - have been referred for misconduct, which Mr Bartley said was easier to identify.
John Bangs, director of education for the National Union of Teachers, said it was wrong for the GTC to have any responsibility for teacher competence.
"In the vast majority of cases it is the nature of the school itself that stops a teacher doing their job properly," he said. "Competence should be an issue for employers. It's not a surprise that referrals are not being made by local authorities who understand the individual circumstances of cases."
John Dunford, general secretary of the Association of School and College Leaders, said some heads found it difficult to carry out proceedings against incompetent staff because of a lack of support from local authorities.
"The system needs to be changed because incompetent teachers are doing themselves no favours by moving schools and finding their professional lives equally difficult," he said.
"I hope the GTC will investigate a process which supports teachers in making a career change where that is in their best interests."
Pupil boredom, pages 12-13.