LARGE sections of Blackburn's River Darwen were turned red after dye spilled out from a sewer.

The dye came out of an overflow in Mill Hill Bridge Street into the river from about 5.30pm yesterday, and travelled downstream, through Witton and Pleasington.

Onlookers in Witton Park were confronted with the strange sight of the red river, against the backdrop of green fields.

Analysts found that the dye was inert that is neither alkaline nor acidic and of no threat to the fish, or ducks, that live in the river.

However, the Environment Agency and United Utilities were investigating whether the contamination was due to a blockage in the sewer, or someone maliciously dumping the dye.

Today it was looking more likely that the red dye was legally allowed to be disposed of and that there was a problem in the sewer that had caused it to spill out of the and overflow into the river.

Officers found only one company in the town that produced such dyes, but its bosses told them it was not one of its products.

The investigation was therefore continuing today into the origin of the dye.

Station manager Gary Monk, of Blackburn fire station, said: "It was quite a vivid red liquid which came out of the overflow. It may have been a company which is legally able to put the stuff into the sewer.

"But it maybe an unscrupulous company which has done something illegal.

"A sample has been taken away for further analysis to tell us what exactly the product is."

A spokesman for the Environment Agency added: "We are trying to work out where it has come from.

"It does not appear to be oily and has not affected any of the fish."

Inspector Des Barr, of Blackburn police, said they had been notified, but not involved.

He added: "The fire service told us there was some kind of red paint dripping into the river, but it is not a police matter at this time."