Some motorists may have badly damaged their cars, in a fuel botch up in Christchurch

Fuel company BP is getting in touch with customers, after drivers unintentionally put diesel in their petrol cars.

They're reaching out to customers who thought they were filling up with 91 at Russley Road, between 7.30 on Monday night and 10am yesterday.

Fuel Rescue manager Nick has been busy and is expecting more cars to trickle in today once people realise what they've done.

He says it can cause damage - with the potential for diesel to block up catalytic converters, and if the car continues to run for a long time, the diesel can fill up the oil sump.

BP says it's sorry for the inconvenience, and it will compensate customers in any instances where there are proven fuel quality issues.