Essex schools have brought in a private firm to chase up parents of absent pupils with phone calls and texts.

Software firm Truancy Call warns mums and dads their children could be bunking off by making use of automated voice messages - the technology more familiar to most as an irritating means of promising phoney prizes or selling broadband contracts.

Headteachers at Colchester's St Helena School, the John Bramston School in Witham and Alec Hunter High School in Braintree have all paid to subscribe to the service.

It removes the need for reception staff to make time-consuming calls and ensures every unexplained absence is followed up.

But John Bramston headteacher Ted Rowley today admitted it can lead to "embarrassing" mix-ups when the system does not register replies from parents - who then continue to be bombarded with messages or texts throughout the day and evening.

"Things go wrong from time to time," he said. "It is invariably down to human error, but when it is automatic, that creates more aggravation."

Under the system, teachers e-mail a list of missing pupils to Truancy Call as soon as they have taken the morning register.

The firm then texts parents' mobile numbers or leaves a voice message on their landline.