The main suspect in mass shootings at two New Zealand mosques was charged with one count of murder a day after an attack that killed 49 people and wounded dozens, prompting the prime minister to vow reform of the country's gun laws.

Brenton Tarrant, a 28-year-old Australian citizen, appeared in a Christchurch District Court on Saturday and was remanded without a plea until his next scheduled appearance in the South Island city's High Court on April 5.

Handcuffed and wearing a white prison suit, Tarrant did not speak. His court-appointed lawyer made no application for bail or name suppression.