New Zealand Prime Minister Jacinda Ardern on Monday announced a Royal Commission of Inquiry into the Christchurch terror attack.

The independent judicial inquiry is the country's highest-level form of investigation.

"The inquiry will look at what could have or should have been done to prevent the attack," Ardern said at a press conference.

She said the form of inquiry was appropriate for "matters of the gravest public importance."

Such commissions are run independently from the government and are led by a high court judge. They can compel witnesses to testify and organizations to hand over documents, but their findings must be followed up through the courts or the government.

Read more: Jacinda Ardern's government to announce gun law reforms within 10 days

Her cabinet will finalize the terms of reference for the commission in the coming weeks. However it is expected to find out what roles semi-automatic guns, social media and intelligence agencies had preceding the attacks.

On March 15, 50 people were massacred at two mosques in the city of Christchurch. 

An Australian white supremacist has been charged with murder over the attack and is expected to reappear in court next week.

aw/se (AFP, AP)

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