WELLINGTON (DPA) - New Zealand's major media companies on Wednesday (May 1) agreed to "limit any coverage of statements, that actively champion white supremacist or terrorist ideology" when reporting the Christchurch mosque attack trial.

"As a group and as individual editors we are committed to ensuring the outlets we represent cover the upcoming trial comprehensively and responsibly," the statement signed by the editors of Radio New Zealand, Stuff, Mediaworks, TVNZ and NZME said.

Australian Brenton Tarrant has been charged with 50 counts of murder and 39 counts of attempted murder after a gun attack on two mosques during Friday prayer on March 15.

The statement said that, as the victims of the attacks hailed from 12 countries, the media's role was of particular importance as it may be the only mean for many of the victims' friends and families outside New Zealand to follow the trial process.

However, media outlets are also aware that the accused may attempt to use the trial as a platform to amplify white supremacist and terrorist views or ideology.

The guidelines would see media limit any coverage of statements that champion white supremacist or terrorist ideology including the accused's manifesto.

Messages, imagery, symbols or signals, including hand signal, made by the accused or his associates promoting or supporting white supremacist ideology will not be broadcast, the statement said.

The trial date is still to be set.

The 28-year has been ordered to undergo mental health tests to determine if he is fit to stand trial before reappearing in Christchurch High Court on June 14.