POLLUTION has been found in a river in the Brecon Beacons National Park, prompting an investigation.

Natural Resources Wales said there has been a "significant growth" of sewage fungus in streams running into the Afon Llynfi downstream of Talgarth and a reduction in insects living in the river and the streams.

A 5km stretch is believed to be affected and the pollution is thought to have been caused by spreading operations on land in the area, said NRW.

The environment body said sewage fungus is usually associated with polluted water and grows on any surface in response to organic nutrients entering a watercourse.

Steve Morgan, operations manager for NRW, said: "Our officers are investigating to confirm the source of the pollution, gather evidence and to identify those responsible."

The fungus isn’t harmful to the public.

NRW also said there is evidence to to suggest that local groundwater has been contaminated.