John Dunford, general secretary of the Association of School and College Leaders, said: "A rise in unauthorised absence is more likely to occur because schools have tightened up on the definition of unauthorised rather than because of a growth in truancy.
"In particular, schools have become stricter over parents taking their children out of school for holidays in term time."
The statistics provided details for the first time of the reasons why pupils miss school and showed that agreed family holidays accounted for 10 per cent of all school absence, with unauthorised holidays making up a further 1 per cent.
Sickness was the biggest reason of all, accounting for 55 per cent of school absence.
Mr Dunford's comments offer some support for Kevin Brennan, the children's minister, who insisted that unauthorised absence was not the same as truancy. It had increased because schools were getting tough on weak excuses they would once have authorised.
But the figures - which show that about 63,000 pupils skipped class every day, while nearly 273,000 pupils were absent for at least one day a week - do not make good reading for a government that has spent nearly pound;1 billion on anti-truancy initiatives.
Opposition politicians said the figures showed that ministers had not got to grips with the problem.