New Zealand opened a gun buyback scheme on Thursday aimed at ridding the country of semiautomatic weapons similar to those used in the ­Christchurch mosque attacks that killed 51 Muslim worshippers.

Prime Minister Jacinda Ardern vowed in the hours after the March 15 killings that New Zealand's gun laws would be tightened and her government has expedited the change in just three months.

"The buyback and amnesty has one objective - to remove the most dangerous weapons from circulation following the loss of life at Al Noor and Linwood mosques," Police Minister Stuart Nash said.

The Australian man accused of the killings, Brenton Tarrant, is alleged to have used an arsenal of five weapons, including two military style ­semiautomatic rifles (MSSAs), in the attacks on two Christchurch mosques.

Lawmakers voted to outlaw MSSAs, which allow the rapid fire of high-caliber bullets, by a margin of 119-1 in the wake of the worst massacre in modern New Zealand history.

Licenced firearms owners will have six months to surrender weapons that have now been deemed illegal under the scheme, with an amnesty ensuring they will not face prosecution in that period. After the amnesty expires, possession of a prohibited firearms is punishable by up to five years in jail.