Government ministers and union bosses have clashed over prosposals to allow schools to fire under-performing teachers in just one term.

Under the reforms schools could also be asked to share information on whether a teacher is being investigated for poor performance to stop "recycling" of weak staff.

The measures are part of a bid by Government to crack down on poor teaching, amid concerns that it damages children's education.

But two teachers' unions condemned the move as "unnecessary and draconian", with one leader calling it a "potential bully's charter".

Under the new arrangements, first announced last May, schools will be able to remove poor teachers from the classroom in about a term - a process that currently takes a year or longer.

The three-hour limit on observing teachers in the classroom will also be scrapped, to allow schools to decide on observation times.

And teachers will be assessed every year against a set of key skills known as Teachers' Standards.

The measures, to be introduced this September, cover maintained schools in England.

The Department for Education (DfE) said it is also consulting on new proposals covering teacher recruitment, which would see schools passing on information, if requested, to future employers, on whether a teacher is, or has been the subject of capability procedures.

The move would help to deal with the problem of poor teachers being "recycled" - moving from job to job, the DfE said.

Christine Blower, general secretary of the National Union of Teachers (NUT) said: "The changes to the appraisal and capability policies will rightly be seen by teachers as an attack on their professionalism and will anger and depress them in equal measure."

She added: "What the Government proposes is potentially a bully's charter. The union believes that many well-functioning schools, where development and professionalism is prized, will not adopt Mr Gove's model.

"If schools are serious about addressing the issue of teacher competence should it arise, they must do it in a fair fashion and not be constrained by a one-term time limit. It is far better to improve teachers than to seek measures to sack them."

Chris Keates, general secretary of the NASUWT teaching union, said: "This is yet another depressingly predictable announcement from a Government seemingly intent on destroying the teaching profession and state-education.

"The draconian measures announced today are totally unnecessary. There is no evidence which demonstrates that there are problems with the current system."

She said the NASUWT will "vigorously" oppose the changes.

Education Secretary Michael Gove said: "Schools need to be able to dismiss more quickly those teachers who, despite best efforts, do not perform to the expected standard. Future employers also need to know more about the strengths and weaknesses of teachers they are potentially employing.

"Nobody benefits when poor teaching is tolerated. It puts pressure on other teachers and undermines children's education."

Russell Hobby, general secretary of the National Association of Head Teachers (NAHT), said the proposals were in the "best interests" of the profession.

"The simplest way to protect teachers is to be seen to be taking responsibility for our own performance. There is so much good practice out there that I think the profession has nothing to fear," he said.

"Clearer systems of performance management are one way to build up the professional reputation of teachers and get those outside the classroom to let the experts get on with the job.

"Teachers deserve to be regarded as skilled professionals driven by a sense of vocation and making a real impact.

"For those who are clearly unsuited to teaching, it is in everyone's interests - not just of pupils but of the profession's reputation - that, after a fair process, they should be helped to pursue their career elsewhere."