Undercover surveillance has revealed a thriving trade in the illegal sale of fireworks to young children.

Trading standards officers today released video footage of children visiting houses in Middlesbrough to purchase rockets and powerful air bombs from adults.

Acting on tip-offs from the public, officers have been staking out privately owned and council properties and filming the illicit transactions taking place there.

Their investigations have highlighted a booming black market; in one house alone this week, almost 160 rockets were seized.

No one has yet been charged with any offence, but Middlesbrough Council is working with police to gather evidence.

In one video sequence, a dozen youngsters - some appearing to be as young as 11 - are seen trooping into a garden and buying rockets, which they then let off.

In another, a teenage boy casually knocks at a front door and hands a shopping list to a man. He then cycles off with a parcel of fireworks.

John Wells, head of Middlesbrough Council's trading standards, said the town did not have a problem with shops selling to youngsters.

"The big problem is selling from home. This year we hope we are taking pre-emptive action.

"We have a dedicated hotline which people can ring to report this activity and since it was launched a few weeks ago we've had approaching 30 calls.

"A number of premises are currently under detailed surveillance. Once we have reasonable cause to suspect there has been an offence we apply for a warrant and go with police to search the property."

It is illegal to sell fireworks without a licence and illegal to sell them to anyone under 18. Those convicted of doing so face heavy fines and eviction from their homes if they are council tenants.

Traders in Redcar and Cleveland recently signed up to a three-week embargo on the sale of fireworks prior to November 5.

South Bank shopkeeper and anti-fireworks campaigner Pearl Hall said it had had a "marked effect" on the number of youths letting off fireworks in the streets. "It has been marvellous. You can walk down the street without fear. All the councils should do it."

Middlesbrough Council's fireworks hotline number is (01642) 728002.