The Conservatives have renewed calls for the resignation of Education Secretary Estelle Morris, after she accused Iain Duncan Smith of "insulting" A-level students.

You should do the decent thing and resign

Damian Green to Estelle Morris

A Tory spokesman accused Ms Morris of using "cheap" tactics to deflect attention from her "incompetent" handling of the recent A-level crisis, which led to 1,220 papers being re-graded.

The row blew up earlier on Wednesday when Mr Duncan Smith claimed no one now knew if A-level results were "worth the paper they are written on".

In a letter to the Tory leader, Ms Morris said A-level students would be horrified and upset by what she calls his "outrageous" statement.

'Slur'

Prime Minister Tony Blair branded Mr Duncan Smith's comments "totally irresponsible" and a "gross insult" to students and teachers.

The National Union of Teachers also stepped in, accusing Mr Duncan Smith of using the debacle over A-level grading to score "cheap political points".

Liberal Democrat education spokesman Phil Willis said the Tory leader's comments were "an outrageous slur on the efforts of British schoolchildren".

But Tory education spokesman Damian Green said Mr Duncan Smith was merely echoing the views of former chief inspector of schools, Mike Tomlinson.

'Worrying'

In his recent report on the A-level debacle, Mr Tomlinson said there was uncertainty over what the qualifications watchdog thought was the standard for A-levels and AS-levels.

In a letter to Estelle Morris, Mr Green quotes Mr Tomlinson as saying: "After a month of enquiries, I still don't know what the standard ought to be.

"It is worrying that we have an examination system where the standards have not been adequately defined for examiners, teachers and pupils."

Mr Green goes on to say that "both Iain and Mike Tomlinson" are making the point that "faith in A-levels has been heavily damaged" by government "incompetence".

He tells Ms Morris: "Both you and the prime minister should be apologising to all those who have suffered because of your incompetence, and you should do the decent thing and resign."

Confidence crisis

Mr Duncan Smith re-ignited the row over A-level standards on Wednesday, as he took on Mr Blair in the first prime minister's questions since MPs returned from their summer break.

"Right now faith in A-levels has been shaken to the core," he said.

Estelle Morris has come under pressure in recent months

"Nobody even knows whether they are worth the paper they are written on."

The Tory leader also criticised ministers for "blundering" in the row over two boys reinstated after being expelled for threatening a teacher.

And he repeated his party's demands that AS-levels be scrapped.

Mr Blair rejected that call and emphasised it was the Tories who in 1996 had welcomed recommendations for the creation of AS-levels.

He condemned his counterpart's remarks about A-level standards as a "gross insult" to pupils and teachers across the country.

'Irresponsible'

Mr Blair was apologetic to those students hit by the exams uncertainty this summer.

"It is absolutely wrong they should have been put in that position and we accept full responsibility for it," said Mr Blair.

"But to say that A-levels and the students who have got those A-levels that they are not worth the paper they are written on is totally irresponsible."

Classroom discipline was the other major education flashpoint in the first prime minister's questions since MPs returned from their long summer break.

Mr Duncan Smith repeated his party's calls for the abolition of kind of independent appeal panels which reinstated the two expelled boys.

Blunders

He criticised the decision to allow the panels to overrule the decisions of headteachers.

Attacks on teachers had quadrupled since Labour came to power, said Mr Duncan Smith.

The prime minister was unmoved by the attack, saying scrapping appeal panels would not be the "right thing to do".

He stressed that appeal panels had been introduced by Tory ministers in the 1980s.

The Commons exchange came before it emerged that one of the boys at the centre of the dispute had agreed not to return to Glyn Technology School in Epsom, Surrey.