Government figures for 2006/7 show the number of school days missed due to unauthorised absence fell by 1.11 per cent compared with the previous year.

Days lost due to the non-attendance of persistent truants also fell, by 1.6 per cent.

But around 3,400 of the city's 64,900 pupils are still classed as persistent truants - accounting for a third of all reported absences.

And almost 50,000 school days were lost due to unauthorised absences during the autumn term, the figure falling to 45,300 in the spring session.

For the first time the statistics reveal the reason for absences being unauthorised - and simply not turning up for classes is not the only factor.

Pupils are often marked as absent if they are late, while families taking unauthorised holidays also significantly inflate the figures.

Sheffield education chiefs are planning a concerted campaign against such holidays later this year, with a tougher approach expected against parents who insist on taking vacations in term time.

Schools have also been instructed to mark absences as unauthorised if pupils come up with flimsy excuses or claims of medical or dental treatment without sufficient proof.

To tackle the attendance problem, truancy sweeps have already been extended across the city, while more parents are now taken to court over poor attendance.

Sheffield's cabinet member for children's services Coun Harry Harpham said he would not tolerate persistent absence from school, or any unauthorised absence.

He added: "We have families in court this week for failing to send their children to school, and take a very hard line on families who refuse to allow their children to be properly educated."

Nationally truancy rates rose to record levels last year, with 63,000 pupils skipping class every day, despite more than £1 billion being spent on schemes to boost attendance.

But overall absence, which includes children off sick with permission, has reached a record low.

Children's minister Kevin Brennan said the statistics were showing positive trends.

He said: "It is no surprise when the 'unauthorised absence' figure goes up because schools are taking a tougher stance on weak excuses they may once have authorised.

"Dubious absences are now being rigorously queried, rather than overlooked, as they may have been a decade ago."

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