TWENTY-one children have been caught with drugs on school premises in Gwent in the last four years, new figures reveal.

Data from Gwent Police shows cocaine, a class A drug, was among the illegal substances seized in the 21 incidents.

Teachers described the figures as a "worry", and "the tip of the iceberg of what young people are encountering on the streets".

The data, collected from 34 police forces dating back to 2011, was obtained by the Press Association under the Freedom of Information Act.

Cannabis, the most widely used illegal drug in the UK, was involved in more incidents and offences than any other - 625 - while cocaine was present in 27 cases.

In Gwent, 16 offences involved cannabis, two involved amphetamines and one, cocaine.

Mephedrone was also confiscated twice by Gwent Police over the four years.

Nationally, four incidents involved children under 11.

In Gwent, seven incidents involved 11 to 14 year olds, three 15 to 16-year-olds, four 17 to 18-year-olds and seven over 18s.

Chris Keates, general secretary of the NASUWT teaching union, said: "Any incident of drugs on school premises is worrying as it will often only be the tip of the iceberg of what young people are encountering on the streets.

"Teachers and school leaders are always alert to the potential for young people being involved in drug or alcohol abuse.

"Unfortunately, many of the programmes and specialist support on which schools could rely to assist them in supporting and educating young people in the perils of substance abuse have been cut under this coalition government."

Nationally, the vast majority of incidents occurred on school premises (752), although colleges and universities in the force areas also reported incidents.

In Gwent, 16 incidents happened in schools, two in colleges and three at universities.