A river has been polluted with 120,000 gallons of slurry after an accidental spill at a farm in Pembrokeshire.
The slurry has spread to the Afon Dyfan, a tributary of the River Teifi, near Cilgerran. The effect of the spillage is being investigated by Natural Resources Wales (NRW).
A number of dead fish have been found, said Ioan Williams, from NRW.
The farmer reported the spillage immediately and the slurry store has since been secured.
Mr Williams said the incident was caused by a "technical issue" with a slurry store.
"It's still early days. Our investigations are continuing," he said.
"We have officers working with the farmer to try and lessen the impact on the environment."