Hundreds of people are affected by an E-coli scare, which has hit around 120 bores in North Otago.

People using bores in the Lower Waitaki plains area north of Oamaru have been advised not to drink the water.

Otago Regional Council chief Sarah Gardner says it's too early to say if the contamination is linked to the dairy industry.

She says there are also a number of septic tanks in the area, and officials are working to identify the source of the problem.