Australian Brenton Tarrant appears in a New Zealand court where the suspected white supremacist is charged with an additional 49 counts of murder at two mosques in Christchurch.

The Australian man arrested over New Zealand's mosques shooting massacre will face a total of 50 murder charges and 39 attempted murder charges when he appears in court on Friday, police say.

Christchurch police launch an urgent investigation to find out whether a man who died after an early morning stand-off with armed officers had links to mosque attacks which killed 50 people.