New Zealand police have filed terrorism charges against the individual behind the killings of 51 worshippers in March.

The shooter, who is an Australian citizen, is facing 51 charges of murder and 40 charges of attempted murder in addition to the terrorism charges just brought against him.

A potential maximum penalty of life-in-prison accompanies the new charges facing the 28-year-old.

The next court hearing for the shooter has been scheduled for June 14. Findings from a mental health examination ordered by a judge last month will assist in determining whether or not the shooter is fit to stand trial.

The attacks on March 15 left more than 50 individuals dead and 47 injured when a shooter opened fire at two Christchurch mosques in New Zealand.

New Zealand Prime Minister Jacinda Ardern called the incident "one of New Zealand's darkest days."