On Monday, Ms. Ardern said the second set of proposed restrictions would also have prevented the attacks.

“The suite of measures would have made it considerably harder for the terrorist to purchase guns in the way he did,” she said on Monday in a statement via text message. “He would have had to pass a good character test and the register would have alerted the police to the type of gun purchases the terrorist was making.”

The man accused of the attack is an Australian citizen who moved to New Zealand more than a year before the shooting. He acquired a New Zealand gun license and an arsenal of weapons and ammunition that he was not required to register.

Under the new rules, foreign visitors to the country — those intending to stay in New Zealand for less than a year — will be barred from buying guns. People visiting for hunting trips would have to either rent guns or bring their own and register them with the police, provided they were not among the models that were recently banned.

New applicants for gun licenses will be subject to tougher checks to ensure they are “fit and proper” people, and the standard for the character test will be enshrined in law; previously it was only part of police guidelines.