UPDATED: 4.32PM Police will be redeploying a handheld breath screening device, which saw people wrongly prosecuted for elevated breath test readings.

Last October 400 of the Draeger 7510 devices were withdrawn, after a malfunction affected the accuracy of alcohol readings recorded by 17 percent of the machines.

Police withdrew court action against 19 people prosecuted as a result of higher breath test readings caused by the fault.

Extensive scientific testing at Draeger's laboratory in Germany has resolved the issue.

From tomorrow 200 of the machines will be rolled out in test mode, to make sure they work properly in field conditions.

Another round of accuracy tests will follow, before all 400 devices are reintroduced in August.

All of the costs associated with the withdrawal, testing and redeployment of the devices to date are being met by Draeger.