The Hawke's Bay Regional Council and Napier City Council are again warning about pollution after the discovery of what is regarded as a "small" discharge diesel or oil in to the Napier inner harbour on Monday.

The councils say the leak, via stormwater pipes, is a reminder to local industries to check their operations to try to avoid such problems.

A discharge of diesel/oil (hydrocarbons) was reported at the western end of the inner harbour, otherwise known as Te Whanganui a Orotu or the Ahuriri Estuary.

The councils' oil spill responders investigated and narrowed the source to premises attached to the Napier City Council stormwater system.

But Regional Council group manager of Policy and Regulation Katrina Brunton urges staff to check their stormwater on-site to make sure everything is operating correctly, and asks that they contact the HBRC's pollution hotline (0800 108838) if they have an oil interceptor or if they are aware of an accidental or intentional spill in the area.

Regional Council and Napier City investigating officers will be in the West Quay area investigating premises and seeking potential sources to locate the origins of the pollution "and stop it as soon as we can," Brunton said.

She said it's a reminder to ensure oil spill response plans, spill kits, bunding and interceptors have been cleaned to ensure no pollution escapes into the environment.

- Hawkes Bay Today, NZ Herald