The Diploma will cover all the sciences
The introduction of one of the government's new Diploma qualifications for England has been delayed by a year.
Schools Minister Jim Knight said the delay was needed to make sure the advanced level science course was the best it could be.
The qualification, equivalent to three A-levels, will now be taught in schools from September 2012, rather than 2011.
Officials say there are no delays to other Diplomas, which were first rolled out in some schools last September.
Foundation and higher level science Diplomas, equal to GCSEs, will go ahead as planned from September 2011.
It is understood the problems centred on disagreements over what should make up the common core of the advanced science Diploma, because of the various subjects involved.
Those charged with drawing it up were "struggling to devise a Diploma that would meet everyone's needs", an insider told the BBC.
There was the added issue of how to fit maths into the Diploma.
The aim of the qualification is to equip students for work in science-related fields or to go on to higher education.
Diplomas were designed to bridge the divide between academic and vocational qualifications and are being offered at various levels.
Courses already being rolled out in schools and colleges are in engineering, construction, IT, media and health. Eventually 17 courses will be offered, including Diplomas in humanities, science and languages.
Mr Knight said the decision about the advanced science Diploma had been made after a consultation found further work needed to be done.
"The new science Diploma needs to be the very best it can be to provide a significant boost to both participation and attainment in science - so we can't afford to rush it," he said.
"The other Diploma lines already have the backing of employers, experts and higher education. I want to ensure that quality across the board."
Sir Mark Walport, chairman of the government's Science and Learning Expert Group, said: "It is essential that we provide the best education in maths and science subjects to young people at all stages of their education.
"It makes good sense to delay the introduction of the advanced science Diploma to 2012.
"We will be consulting widely at the interfaces between schools and higher education and between higher education and the workplace."
The move was welcomed by the science community. Score (Science Community Partnership Representing Education), the body representing the UK's scientific learned societies and science teachers said the advanced Diploma could help to increase the numbers of students studying sciences between the ages of 16 and 19.
But it had raised key issues and concerns with those devising the qualification.
Sir Alan Wilson, the Chairman of Score, said, "The decision to delay for a year is one that we have been pressing for and we are delighted to see government recognise the need for further work."
The group wanted a "clearer vision and purpose for the Diploma", a strong focus on applied sciences and customised supplementary qualifications to prepare students for higher education and work.
The decision to postpone was sensible, said John Dunford, the general secretary of the Association of School and College Leaders (ASCL).
"I welcome the postponement of the introduction of the advanced Diploma in science. Between now and 2011, schools and colleges have a huge amount of curriculum change to implement and it is essential that the authorities get things right first time," he said.
"The recently identified problems with the new GCSE science course clearly illustrate how public confidence can erode when qualifications are introduced with too little preparation."
"If the science Diploma is to be successful, it must be a passport to university science courses and, if it takes a year longer to design a qualification that does that, the delay will be worthwhile."