PM Jacinda Ardern says New Zealand’s cabinet has backed gun law changes “in principle” after the Christchurch shootings.
Fifty people were killed and dozens wounded in attacks at two mosques on Friday.
Australian Brenton Tarrant, 28, has appeared in court and been charged with murder.
The attacks sparked calls for gun law reform, with Ms Ardern saying soon after that “our gun laws will change”.
Speaking at a press conference after a cabinet meeting, Ms Ardern said she expected to have details of the reforms by 25 March, which would be within 10 days of Friday’s shootings.
“We have made a decision as a cabinet, we are unified,” the prime minister told reporters.
New Zealand’s Police Association has called for semi-automatic weapons to be banned, Radio New Zealand reported.
Many public vigils have been held across New Zealand over the weekend for the victims of the attacks, and more are planned for this week. Nine people remain in hospital in a critical condition.
At the weekend, Ms Ardern said the suspect had a gun licence, obtained in November 2017, and owned five guns.
Earlier on Monday, gun retailer Gun City said it had sold weapons to the man charged with murder, but not the high-powered weapon used in the mosque shootings.
Previous attempts to tighten gun laws in New Zealand have failed due to a strong gun lobby and a culture of hunting.
Christchurch shootings: NZ cabinet backs action on gun laws