United Nations Secretary-General Antonio Guterres has paid tribute to the unity displayed in New Zealand following the Christchurch mosque shootings.

Photo: David Rowland/ AFP

Mr Guterres is spending two days in New Zealand during his tour of the Pacific region.

He met with Prime Minister Jacinda Ardern, before she leaves for a Paris summit to crackdown on social media being used for terrorism.

Mr Guterres described his visit as a one of "solidarity and gratitude".

"Solidarity, first of all, with the victims of Christchurch, with their families, with the community, the city, but also with the people and the government of New Zealand."

Every year, since he worked as the UN High Commissioner for Refugees, Mr Guterres has visited a Muslim country during ramadan for a "solidarity visit".

He chose Christchurch for this year's visit to pay tribute to the community's courage and resilience, as well as the unity displayed by New Zealand in the wake of the attacks on 15 March, he said.

Mr Guterres commended the prime minister on her response to the Christchurch attacks and her call to tackle the use of social media to promote and organise terrorism. He expressed his support for the Christchurch Call.

"If I would have to select the two biggest challenges that political leaders face in the world at the present time, I would say it's clearly to reverse climate change and second, to make sure that the new technologies... become a force for good and not a dramatic risk for all."

Mr Guterres said the government's recently released climate change objectives were in line with what the global scientific community see as "essential".

"I don't think there is any other region but the pacific with the moral authority to tell the world that the world needs to abide by what the scientific community is telling us."

The government's Climate Change Response (Zero Carbon) Amendment Bill aims to limit global warming to no more than 1.5 degrees Celsius and to build a country and economy that can cope with the changing climate.

It wants net zero carbon dioxide and nitrous oxide by 2050, but to reduce methane by 10 percent below 2017 levels by 2030, with a provisional reduction of 24 to 47 percent by 2050.

Mr Guterres also wished the prime minister a happy Mother's Day.

He was officially welcomed to New Zealand at Government House in Auckland, will go to Christchurch, and will give a lecture at the Auckland University of Technology.