Police say an Invercargill motorist reporting a speeding driver on State Highway 1 today, may have saved many lives

The motorist informed Police of a car going at least 50 kilometres an hour over the open road limit, swerving through northbound traffic heading towards Gore.

Police pulled over the driver, aged 18, without incident, saying he was more concerned with the speed they had to do to catch him, rather than his own speeding.

It's the second time the driver has been stopped for speeding, in as many weeks.

The driver will appear in court on two charges of dangerous driving, and his license has been suspended for 28 days.