Those responsible for polluting the River Trent in Staffordshire with the chemical cyanide will be prosecuted, the Environment Agency has said.

Thousands of fish have died and people were warned to stay away from the river while the pollution, between Stoke-on-Trent and Yoxall, is controlled.

The agency said it aimed to prosecute under the Water Resources Act.

A spokeswoman would not give more details of where the cyanide came from for legal reasons.

Environment officers, who began pumping oxygen into water on Tuesday night, have managed to greatly reduce levels of pollution on the 30-mile (48 km) stretch, the agency said.

The public, farmers, anglers, boaters and animals have been warned to stay away from the water as a precaution.