Dozens of business people were turned away yesterday as they tried to dump loads of trade rubbish at household waste depots without paying a fee.

It was the first day of a permit system launched to prevent firms tipping refuse illegally at 17 civic amenity sites in County Durham by pretending to be private ratepayers.

Residents can still take house and garden rubbish to these sites free of charge in their cars and other private vehicles, such as fully-glazed jeeps.

But the crackdown means anyone arriving with a trailer, van, truck or other commercial vehicle must produce a permit from Durham County Council before being allowed through the gates.

As the first callers were turned away yesterday, a council spokesman said many firms had been using the household sites to avoid paying charges of up to £45 a tonne.

It was estimated that rogue tippers could cost the council £1m a year - or £4 for every household in the county -if they were not brought to book.

Staff at all 17 sites were also told to stop people walking in carrying loads of rubbish, as they had probably parked vans or trucks nearby to try to beat the permit system.

An official at a site at Stainton Grove, Barnard Castle, said: "Some people will try anything to avoid paying, but we will stick to the new rules and stop them coming in."

Councillor Brian Myers, the council's cabinet member for waste management, said, "The illegal use of sites has been growing at an alarming rate. It has risen by 20 per cent in the past three months. It is essential that we achieve a substantial reduction."

Since January, 15 per cent of rubbish found in household waste recycling centres came from trade and commercial sources and council official believe this may be closer to 20 per cent by the end of the year.

The council warned that it has also put in place effective measures for people who may be tempted to ignore the permit scheme and fly-tip.

In partnership with the five district councils, the county council has employed a Fly Tipping Officer, whose job is to investigate cases of fly-tipping and prosecute those responsible.

A spokesman for the council said: "There really is no escape. Even if he is not there when the rubbish is dumped, we can track them down. Often, there are items in the rubbish that lead straight to the person responsible."

Anyone wanting to obtain a permit can contact the council on 0191-383 5656 or by email on www.durham.gov.uk/environment/permit

They can also be requested by writing to the Waste Management Business Unit at County Hall, Durham DH1 5UQ, or by fax on 0191-383 3231. They are also available at libraries.

A separate permit is needed for every load deposited. Up to five permits can be requested at a time, and they remain valid for two weeks.