WELLINGTON - New Zealand Prime Minister Jacinda Ardern said on Monday that the cabinet has decided to reform the gun law within 10 days.

The reform of the gun law is agreed by three coalition partners -- New Zealand Labour party, New Zealand First Party and Green Party, Ardern told a press conference after a cabinet meeting.

However, she refused to reveal any details of the upcoming reform.

A national memorial service for the mosque attacks in Christchurch, which left 50 people dead and 50 others wounded, will also be held as soon as possible.

Ardern also said that an inquiry will look into the Christchurch terror attacks.

At another press conference, New Zealand Police Commissioner Mike Bush confirmed the gunman acted alone, but might have had support.

"We believe absolutely there was only one attacker responsible for this," Bush said.

But he did not rule out support of other people and said it was "a very, very important part of our investigation."