ENVIRONMENT bosses have said a pollution spill that left a 50 metre stretch of the River Calder in Whalley covered in white foam was probably caused by detergent.

Pollution inspectors were called to the River Calder late on Thursday after a white frothy substance and dead fish were spotted in a stretch of the river at Bridge End. Councillor Chris Sterry was called to the river at 9.30pm by residents who spotted the white foam floating towards Whalley Abbey.

He said: "A stretch of the river at Bridge End was covered in foam for about 50 metres and residents were out with plastic bottles collecting samples.

"Whatever was in the water had clearly been whipped up by the wier upstream and I hope the authorities do all they can to find out what caused this."

Environment Agency inspectors were called out at 10pm and worked through the night to discover the source of the pollution.

But they returned to the scene during daylight hours after drawing a blank and conducted investigations throughout the weekend.

A spokesman today said: "We were unable to find any dead fish and took samples of the water for analysis in our laboratories.

"We have not been able to discover the source of the pollution, but it was almost certainly caused by a detergent of some kind.

"The incident looked more dramatic than it actually was, but we are working to discover what caused it."