They spoke out as statistics were released showing that 13,470 young people in Wales have so far applied for means-tested education maintenance allowances (EMAs), worth pound;10-30 a week.
Nearly 10,000 (74 per cent) applications have been approved, with 2 per cent rejected and 24 per cent outstanding. The Secondary Heads' Association Cymru supports initiatives aimed at reducing Wales's high drop-out rate.
Around 12 per cent (13,300) of 16 to 18-year-olds are not in education, training or employment.
But it says the EMA system - which requires weekly reports on each student's attendance plus twice-yearly reviews - is too bureaucratic and schools are not receiving sufficient funding to cover the staff time involved.
At Croesyceiliog comprehensive, Cwmbran, around 42 out of 110 Year 12 students receive EMAs. Head Hel ne Mansfield, who is also vice-president of SHA Cymru, said the school had been given pound;2,005 a year for administering the allowances. But she estimates it costs nearer pound;5,000 a year to pay for admin staff and supervision by senior managers, whom she believes should make decisions where, say, poor attendance could mean loss of the allowance.
"With every child, we have to draw up a learning agreement. Twice a year we hold reviews. Every week we check attendance, and all information has to be sent to the firm monitoring EMAs," said Mrs Mansfield.
An Assembly government spokesperson said: "We have made a generous financial provision - pound;70 per EMA recipient for schools and colleges with 10 or more EMA students. Therefore if they have a hundred EMA students, they receive pound;7,000."
Statistics released yesterday show most (77 per cent) of the approved EMA applications were from young people whose families earn less than pound;19,630 a year, entitling them to the maximum pound;30-a-week allowance.
Students in FE colleges accounted for just over half of all successful applicants. More college students (81 per cent) are receiving the maximum pound;30 than school sixth-formers (73 per cent).
Jane Davidson, education and lifelong learning minister, said: "I am very impressed with the take-up of the EMA scheme in Wales."
opinion cymru 23 www.wales.gov.ukstatistics