Twenty one people have been arrested – with 16 charged for drugs offences – as part of a Herts police operation against county lines gang activity in Stevenage.

Last week, officers from Herts police's operational support and operational intelligence groups executed warrants following a seven-month investigation into organised crime and class A drug supply networks.

The operation focused on county lines - the name given to describe drug dealing which involves criminal networks from urban areas expanding their activities into smaller towns and rural areas.

It often involves the exploitation of children, as gangs use young people and those with mental health or addiction problems to transport drugs and money.

The following were charged with supplying class A drugs:

Devon Redhead, 20, Palmerston Court, Stevenage. Kelly Taylor, 45, of Harrow Court, Stevenage. Ryan Thompson, 37, of Boston House, Stevenage. Mark Ward, 25, of Chertsey Rise, Stevenage. Odane Stone, 24, Kingfisher Way, London. Sean Meloney, 23, of Cowgate Road, London. Andrew Webb, 30, of Marlowe Road, London.

The following were charged with posession with the intent to supply class A drugs:

Nicky Horgan, 47, of The Willows, Stevenage. Mo Thomas, 40, of no fixed address and Reese Mullings, 21, of Hydean Way, Stevenage. An unnamed man and woman, both from Stevenage, were also arrested but released under investigation.

The following were charged with being concerned in the supply of class A drugs:

Kim Brown, 42, of The Willows, Stevenage. Sophia Battle, 33, of Archer Road, Stevenage. Josh Thomas, 33, of Southwark Close, Stevenage. Paul Bennett, 22, of Northbrooks, Harlow.

Karrell Mckoy-Williams, 24, of Lion Road, London and Austin Ugwumadu, 24, of Adelaide Road, London, have been charged with conspiring to supply class A drugs.

Three boys, one 15-year-old and one 16-year-old from Hitchin, and one 16-year-old from Stevenage, were also arrested and released under investigation.

Detective Inspector Mark Clawson, who led Herts police's Operational Intelligence Team's operation, said: "We put together this operation to alleviate the issue of County Line dealers coming into Stevenage.

"These operations will send a clear message to gangs that they will not be allowed to operate in Hertfordshire."

Stevenage's Chief Inspector Alicia Shaw said: "We have made a significant impact on the county lines networks operating in Stevenage, disrupting gang activites and the supply of drugs."