The number of children who go missing during school holidays is on the rise, the Telegraph & Argus can reveal.

New data shows 96 children failed to return to school as expected after the long summer break last year, the highest number in three years and a 55 per cent rise on the previous year’s figure.

More than half of the children – 54 of them – were still unaccounted for a month later, despite the efforts of the local authority to trace them or their families. The Telegraph & Argus requested Bradford’s figures for the past three years under the Freedom of Information Act.

Each year, many children reported missing from school rolls turn out to have moved to a different school but other children and their families are never traced. Campaigners fear some of them could have been taken overseas by their families to be forced into marriages. The authority’s education boss, Councillor Ralph Berry, said the rise could be down to the increasing number of Eastern European migrants, who could be moving back to their countries of origin without telling their children’s schools.

He said: “In many cases it’s a family that has moved and neglected to tell us.

“Because we have got increasing migration from Eastern Europe, it goes some way to explaining some of this.

“What we have to do is make people aware that they should tell us, because people get worried. People knock on doors, people will ring up. Schools are very, very vigilant about this – and rightly so.”

But forced marriage campaigner Jasvinder Sanghera, a former victim herself who helps others through national charity Karma Nirvana, said the figures were one way of monitoring how many children were being taken abroad to be forced to wed.

Miss Sanghera called for detailed statistics to be made more widely available across the country, because they were such a useful indicator of the problem of forced marriage.

She said: “Because of the link, we have got to be able to interrogate the statistics and have them at board meetings every single month, to look at these. Otherwise, that victim is going to become invisible to the system, just like I was when I went missing when I was 15.” She said schools in Bradford should do more to raise awareness of forced marriage to stop victims “slipping under the radar”, as she feared the problem was being “woefully under-reported” in the district.

Miss Sanghera said last year she spoke at a free-to-attend forced marriage seminar in Bradford. She said all secondary schools in West Yorkshire had been invited, but only two of them sent a representative along.

She urged all schools to display Karma Nirvana’s awareness-raising posters or to contact the charity if they needed guidance. Miss Sanghera said of the calls made to Karma Nirvana’s helpline in the last year, only 100 had been from the Bradford district.

She said: “For me, that is woefully under-reported. Bradford should be one of the top five calling areas.”

Miss Sanghera said she feared those making the calls represented the “tip of the iceberg”. She said the law would change soon to make forced marriage an offence, which represented an ideal opportunity for an awareness campaign locally. And she added: “My question to the local authority is, ‘What are your plans with respect to ensuring that people in Bradford know it’s against the law to force somebody to marry?’ ”

Coun Berry said the local authority took the issue very seriously and had in the past applied for court orders to stop forced marriages from happening.

He said: “We are constantly trying to raise awareness of this and if need be we take the appropriate legal measures. It’s a delicate and difficult area.”

And he warned the problem wasn’t just confined to Asian communities, or to girls. He added: “It’s like anything, you have constantly got to be on the ball and looking out for it. Though it mainly affects girls, there are occasions I have heard of in other areas affecting boys.”

He said schools played a crucial role in identifying potential victims and stepping in, as did community organisations, voluntary organisations and youth workers. And he said school friends were particularly good at recognising when something was wrong and raising the alarm.

Of the 96 missing children reported in September, 12 were found to have enrolled at other schools in the Bradford district, while 18 had moved to schools outside the district.

Nine children had left the country with their families and three more have been located, with their families being given support by Bradford Council to find an alternative school place.

In 2012, 62 pupils failed to return to school as expected after summer. Only one child was never traced.