Jacinda Ardern announces Royal Commission into security agencies after Christchurch attack

Prime Minister Jacinda Ardern has announced there will be a Royal Commission of Inquiry into New Zealand's security and intelligence agencies after the Christchurch attack.

The actions of the Government Communications Security Bureau (GCSB) and the New Zealand Security Intelligence Service (SIS) leading up to the March 15 shooting will be scrutinised.

In her post-Cabinet press conference on Monday, Ardern said as well as mourning the 50 people killed, New Zealand had legitimate questions about how the massacre was able to happen.

The alleged gunman was not on any security watchlists here or in his native Australia.

The announcement comes a day after National leader Simon Bridges called for a Royal Commission into the attack, as well as for the country's security legislation to be revised.

"We need to understand whether this could have been prevented," he said. "It will need to ask hard questions about whether our security and intelligence agencies had their focus in the right places."

In the wake of the massacre, experts have said authorities were "looking in all the wrong places" by focusing on jihadi terror rather than a burgeoning homegrown white supremacist movement.