It is the first time that Taser has suggested there is any risk of a cardiac arrest related to the use of its 50,000-volt stun guns, with critics calling it a stunning reversal for the company.
Green Party police spokesman Keith Locke said it was a step forward for police to aim slightly lower, but the 50,000 volt shock could still have a deadly effect on someone with a heart condition.
"It's good our police are now admitting that Tasers are dangerous. In North America over 300 people have died after being tasered, many of them people with a heart problem."
Assistant Commissioner Viv Rickard said New Zealand police had modified their training after receiving a memo from Taser at the weekend.
He said Taser advised that by "lowering the preferred target zone by a few centimetres to lower centre mass, effectively targeting either side of the belt buckle, this will incapacitate the offender as necessary and reduce the already low risk of cardiac arrest even further".
Mr Rickard said police had an independent medical advisory group which considered all the evidence from deployment of the Taser in all situations.
"Police are as anxious as anyone to ensure that when we deploy these devices, we not only effectively stop violent offenders but we do so it in the safest manner possible."
Since reintroduction of the stun gun in Wellington and the three Auckland districts in December 2008, it has been deployed 78 times and discharged six times.
The people shot all received immediate medical assistance in accordance with standard operating procedure without any adverse health effects, Mr Rickard said.
More than 3500 front line New Zealand police officers will have access to nearly 700 Taser electronic stun guns by the end of next year.
The quick introduction of the Taser was widely criticised here, but generally supported by police themselves. A United Nations report subsequently described the stun guns as a "form of torture".
Campaign Against The Taser, a group fighting their introduction here, said they produced major health and safety issues.
"The Taser administers a severe electric shock and targets are often already in an agitated state, with an increased heart rate, so they are more vulnerable to fatal or permanent injury," group spokeswoman Marie Dyhrberg said earlier this year.
The New Zealand Council For Civil Liberties said there needed to be far more research into the health effects Tasers could have on people with pacemakers and those with mental health problems.
