Ministers' planned revolution in sixth-form study next year could be ruined by university conservatism and apathy, college and school leaders have warned.
Funding shortfalls could also undermine the plans, they said.
Ministers hope that a reformed 16 to 19-year-old curriculum, to be introduced in September 2000, will encourage students to study a much wider range of modular subjects at A level and to cross the traditional divide between academic and vocational qualifications.
But a joint group of college and school representatives has warned that students may spurn the new study plans - and opt for more traditional routes to university - for fear of being handicapped by unclear university admission requirements.
Ministers have said that they hope students from September 2000 will opt to study five or more new AS levels - worth half a full A level - in the first year of sixth-form and specialise in three full A levels in the final year.
Reforms to general national vocational qualifications are designed to encourage students to mix modules of both vocational and academic exams. A new key skills exam will also be introduced.
But school and college leaders fear that universities are being non-commital over the reforms, leaving students to guess how well received their study decisions will be.
In early July the Joint Associations Curriculum Group, which includes the Association of Colleges and the Secondary Heads Association, wrote to the Committee of Vice-Chancellors and Principals warning of the "urgency" with which universities should share their views.
Judith Norrington, AoC director of curriculum, said: "Universities don't have to worry about the reforms for another three years. We have to guide students about their choices now."
Geoffrey Copland, Westminster University vice-chancellor and chair of the CVCP's Learning and Teaching Sector Group, conceded that students would "play safe" and make traditional choices without clearer guidance from universities.
He said that universities generally welcomed greater breadth, but were also concerned that higher workloads could lead to students sacrificing the extra curricular activities valued by universities.
The AoC warned this week that the Further Education Funding Council's plans to fund the new curriculum - which will require longer teaching hours and more bureaucracy - are inadequate.
The FEFC has earmarked Pounds 20 million to meet the changes, about Pounds 2,800 per A-level student. But the AoC believes that to deliver ministers' ideal package - five AS levels converting to three A levels - colleges will need more than Pounds 3,000 per student.