Sixteen-year-olds in England should not be restricted to a choice of A-levels or T-levels, business leaders say.
The new Technical levels, or T-levels as they will be known, will be introduced from 2020.
The Confederation of British Industry says the government needs to avoid "premature" cuts to other qualifications such as Btecs.
Ministers have been consulting on withdrawing money from qualifications that may overlap with T-levels.
They have made it clear they would prefer students who want to study choosing from these two types of qualifications after GCSEs.
In a consultation that has just closed, the government has asked for views on withdrawing public funding from qualifications for 16 to 19-year-olds that overlap with either A-levels or T-levels.
Any qualifications that aren't proven to help teenagers get into further study or work would also be under threat.
While there is support for the principle of a simpler system, with strong technical options for students, many organisations are expressing concerns about too much change too quickly.
The Confederation of British Industry has told the government it "must not underestimate the scale of the T-level reforms and the impact of prematurely ending funding for existing qualifications."
John Cope, the CBI's head of education and skills, said: "Bringing clarity to an often confusing landscape of 13,000 technical qualifications is long overdue, but must be done gradually with time for employers and providers to adapt."
At the moment around 200,000 16 to 19-year-olds study each year for either a Btec or one of the thousands of applied general qualifications.
These include certificates or diplomas in subjects as varied as engineering, music technology, business and health and social care.
The government has suggested that too many of the 12,000 qualifications on offer to teenagers may be either obsolete or not rigorous enough.
But Geoff Barton, general secretary of the head teachers union ASCL, said there was a risk of narrowing the options too soon for teenagers.
"Thousands of 16-year-olds get decent GCSE passes but miss out on the higher grades, and aren't certain whether their best bet in the future is to go down an academic or technical path.
"Btecs are a really good choice for them as they keep their options open."
He added that some teenagers needed time to work out whether an apprenticeship, work or university would suit them.
"It would be very tough on these young people to force them to choose between T-levels and A-levels.
"There is a real risk that they may start courses which they find don't suit them and then drop out of education altogether."
One of the other concerns raised in the submissions to the government - seen by the BBC - is the risk of "cold spots" where new T-levels may not be rolled out initially.
A core part of the new T-level qualifications will be extensive workplace experience, which means they will not all initially be available across the whole of England.
The Federation of Small Businesses said change should be gradual and that "the system should not be reformed until all students in England are able to access all T-level routes that will eventually become available".
David Hughes, chief executive of the Association of Colleges, said it was important to remember that 40% of people going to university didn't rely just on A-levels, and that many adults would need options other than T-levels.
"You don't switch off funding for qualifications that are being used until you have something that is demonstrably better," he said.
A second stage of the consultation is expected later this year.
Source: BBC News