A driver has blown over 1000 micrograms during an alcohol breath test - four times the legal limit - leaving the police surprised and disappointed.

The driver was one of 12 who Wellington police found had excess breath alcohol in the region over the weekend.

The breath alcohol limit is 250mg for over 20 year olds.

Wellington road policing manager Matthew Fitzgerald said: "These are not the results we were expecting."

He urged people to have a sober driver or a plan to get home if they were drinking alcohol.

Alcohol and/or drugs were a factor in about a third of all fatal crashes, he said.

Fitzgerald said it was a reminder that communities had a responsibility to drive safely and not take risks.

"Getting behind the wheel after drinking is one of those risks not worth taking," Fitzgerald said.

Police would step up their efforts to deter drink-driving with checkpoints and breath testing at any time.

"Our officers will be out in force anytime, anywhere to deter unsafe driving behaviour. Drivers can expect to see more checkpoints around Wellington," Fitzgerald said.

"So if you are stopped by police, no matter what time of day or the reason, you can expect to be breath tested."

Fitzgerald had a "simple" message for drivers: "Don't risk your life and that of others by driving while impaired in any way."