Environment Agency Wales officers are investigating after at least 100 fish were found dead in a tributary of the River Usk.

The fish were discovered in the unnamed tributary, about one mile from Brecon, at around 1.30pm on Friday 27 January 2012.

There is a large amount of silt in the tributary, and Agency officers are working to establish the cause.

If anyone witnessed the incident, or has any information, please call the Environment Agency's Incident Hotline on 0800 80 70 60.