ENVIRONMENT chiefs confirmed last night that a river had been polluted, causing the deaths of thousands of fish.

Up to 3,000 minnows, as well as trout and dace, were discovered in the River Skerne, between Darlington and Newton Aycliffe, County Durham, on Friday afternoon.

More than 1,000 were found within a 100-metre stretch near the Hallgarth Road Bridge, in Newton Aycliffe.

The Environment Agency was alerted by members of the public and launched an immediate inquiry.

Last night, the agency revealed that it was a definite case of pollution and appealed for anyone with information to come forward.

Fisheries officers were out until 10pm on Friday, examining a four-kilometre stretch of the river, checking on the numbers of dead fish and trying to find any still alive.

Agency spokeswoman Louise Turner said some surviving fish were found among the dead ones, but they did not need rescuing.

Several water samples were taken but initial results which came back on Saturday afternoon did not conclusively reveal the pollutant.

They have been sent to laboratories for further analysis as part of an inquiry, which the agency has classed as a "category one incident" - the most serious it can investigate.

Officers will return to the river today to carry out surveys in an effort to determine whether or not fish are returning to, and staying in, the area.

Ms Turner said: "There is no question in our minds that this was a pollution incident and nothing to do with the hot weather.

"Something has got into the river to cause this damage. It's now just a case of narrowing it down to find what the actual pollutant was."

She said that, if the pollution was found to be deliberate, legal action could be taken against the perpetrator and the agency would be seeking costs.

Darlington Borough Council has erected signs along the riverbank, urging people not to let their children or dogs go into the water.

Anyone with information can contact the Environment Agency incident hotline on 0800 807060.