HUNDREDS of ducks may have been caught up in a spill which polluted a York stream.

Environment Agency officials say the leak of suspected red diesel oil at Osbaldwick Beck was not a threat to the drinking water supply.

The incident was reported to the agency on Tuesday. A clean-up operation started yesterday, with the mystery substance soaked up by booms to prevent it spreading upstream.

A dog walker who spotted pollution in a stretch off Hull Road yesterday morning said hundreds of ducks were affected.

"They were all lying flat on the grass and some were in a sorry state.

"About a dozen looked like they could be about to die. Others were distressed and had oil on their faces and chests.

"When I crossed a bridge over the beck I could smell fuel. The water was full of red streaks," said the Milson Grove resident, who asked not to be named.

"There was a good couple of 45-gallon drums in there - it was just a mess."

But agency environmental manager Peter Stevenson said the incident at Osbaldwick Beck was "relatively minor" and stressed environmental damage was not serious. He said: "There's no threat to drinking water and this will not have a great impact on the Ouse."

An RSPCA spokeswoman confirmed an inspector rescued seven ducks and took them to Minster Veterinary Practice, York.

She said: "We could not contain any more and are going back today to see if we can help more.

"If we can't catch them there's very little we can do. If they're not soiled badly they could clean themselves, but it's a problem if they're covered."

Janet Bird, of Minster Vet's, said the rescued ducks were now "clean and sparkly".

Updated: 11:03 Thursday, December 18, 2003