Child worries; In association with NHS.
The world economic crisis will play a role in the deterioration of children's mental health, he said.
Prof Barry Carpenter, who chaired a national inquiry into mental health, said official figures do not take into account the high incidence of mental health problems among pupils with learning difficulties.
The most recent 2004 data from the Office for National statistics showed that 10% of children had mental health problems.
Prof Carpenter said: "If you combine into that figure what we know about children with special needs - or every five children with special needs we know that three will have a mental health problem - I think the one in 10 is going to creep up as homes start to feel the economic recession."