When school absence rates fell to their lowest levels for six years recently, ministers congratulated teachers and parents for their hard work in combating a perennial education problem. But education welfare officers claim that schools could be "massaging" the figures. They fear that fewer children are being listed as absent because schools are registering pupils as participating in education when they are not at school.
Government statistics released last month showed that the official overall absence rate in state-funded primary and secondary schools fell from 6.1 per cent in the autumn term of 2010 to 4.7 per cent in autumn term 2011.
But the National Association of Social Workers in Education (NASWE) has warned that schools now realise they can take a "flexible" approach to registering pupils, even if they might be truanting. Cuts to the number of education welfare officers employed by local authorities and the growth of academies mean that school registers come under less scrutiny, according to NASWE.
One tactic among schools is to use a registration code (code "B") that records a pupil as not in school but being educated off-site. This does not count towards absentee figures.
"My sense is that the use of the code has probably increased substantially," said NASWE president Julie Parrish. "The incentive for schools has never been greater. Many more schools are effectively unregulated when it comes to school attendance.
"In the most recent government statistical release, there would seem to be a very impressive improvement in school attendance. However, there is doubt regarding the actual change.
"It is not just academies where the possibility of massaging the figures is likely to succeed. Many maintained schools do not now have an education welfare or social work service supporting and challenging them."
Education welfare services are increasingly being cut by councils as they struggle with tighter budgets. Attendance officers say they are less able to hold teachers to account and challenge decisions if schools have bought in their services than if services are supplied by local authorities.
"NASWE members have shared individual examples of headteachers challenging an education welfare officer's role when questioned about coding accuracy," Mrs Parrish said. "They state, sometimes openly, that they are not paying to be challenged in this way."
Even a small improvement in official attendance records can make the difference between schools doing well or not in Ofsted inspections, she added.
Heads' unions reacted angrily to the claims that schools might be falsifying figures. Brian Lightman, general secretary of the Association of School and College Leaders, said schools put significant effort into improving attendance. "There are close guidelines schools are expected to follow on registration," he said. "Schools know if they ignore them they will get into serious trouble."
Russell Hobby, general secretary of heads' union the NAHT, said the improvements in attendance "were real". "Schools want children to be there as much as possible; if they are not there they can't achieve the results they need," he said. "Teachers have put a lot of effort into getting maximum attendance."
But although Chris Keates, general secretary of teaching union the NASUWT, said they were very serious allegations, she added that changes to the education system made this kind of action by schools more likely.
"The increasing fragmentation of the education service is meaning that on many levels, including attendance, children are slipping through the net," she said. "This is being compounded by a punitive accountability regime that drives schools to privilege only those activities that will help them to meet Ofsted criteria and performance league tables."
A Department for Education spokeswoman said: "One day missed from school is one day too many. We expect all teachers to take a tough stance on absence because pupils' school attendance can have a direct impact on their attainment."
6.1% - Overall absence rate in state-funded primary and secondary schools in autumn term 2010.
4.7% - Overall absence rate in state-funded primary and secondary schools in autumn term 2011 - the lowest rate for six years.
15.2m - School days missed due to illness in autumn term 2010.
11.4m - School days missed due to illness in autumn term 2011. Illness was the most common reason given for absence, accounting for 58 per cent of all absence.