Experts are concerned by children's increased use of mobile phones
Two children in Spain have been admitted to a mental health institution to be treated for addiction to their mobile phones, Spanish media report.
The children, aged 12 and 13, were sent to the clinic by their parents, who said they could not carry out normal activities without their handsets.
They were doing badly at school and lying to relatives in order to get money to spend on their phones.
They have been learning to cope without their phones for three months.
Dr Maite Utges, who runs the Child and Youth Mental Health Centre in Lleida, near Barcelona in north-eastern Spain, said it was the first time the clinic had treated children who were dependent on their mobile phones.
"They both showed disturbed behaviour and this exhibited itself in failure at school. They both had serious difficulties leading normal lives," she was quoted in Spanish papers as saying.
The children had owned their phones for 18 months, and their parents had made little effort to restrict their use before noticing how serious their dependence had become.
'Tip of iceberg'
Dr Jose Martinez-Raga, an expert in addictions, said children who developed a dependency on mobile phones, like those who over-used video games, often became irritable, withdrawn and antisocial, and their school performance deteriorated.
He warned these cases could be the "tip of the iceberg", and that mobile phone addiction "could definitely be a danger in the future".
Fears have been raised in a number of countries about the adverse effects mobile phone use may have on children.
Dr Utges recommended that parents not allow their children to have mobile phones until they reached 16 years of age.