The committee's second annual report warns that those under 16 who volunteer a sample may not fully understand the process.
It says that legally taking a sample without written consent, "could constitute assault" and adds that "ethically there is no justification."
The consent form should be signed by the child and also countersigned by the parents or guardian to verify the child's understanding of the process.
The committee adds that samples from 10 to 12 year olds should only be taken "exceptionally". Further research into the ethics of taking samples from under 10s is also being called for.
DNA records of both adults and children should be destroyed once they have been eliminated from an inquiry, says the committee, which also wants to see a ban on child DNA profiles being loaded onto the National DNA Database.
