Jacinda Ardern says her approach to human rights issues in the Philippines and its record on killing drug traffickers is the same of past Governments.

"Our view is that that number of deaths certainly requires investigation and oversight - at the very least," she told reporters in Manila where President Rodrigo Duterte is hosting the East Asia Summit

"There have been attempts by the international community, is my understanding and I believe those have not been accepted.

"But certainly it would be a concern of any country to see that level of death as a consequence of that policy."

New Zealand's Prime Minister Jacinda Ardern during the Opening ceremony of the 31st ASEAN Summit. Photo / AP
New Zealand's Prime Minister Jacinda Ardern during the Opening ceremony of the 31st ASEAN Summit. Photo / AP

One of the last items on her programme at the East Asia Summit on Tuesday is a scheduled meeting with Duterte, who last week told meeting of Filipinos in Vietnam that he had stabbed a person to death when he was aged 16.

"One fight there, another here - at the age of 16, I killed someone. A person, really. During a fight. Stabbing. That was when I was 16 years old, just because we just looked at each other," he said.

CNN reported that he was suggesting his approach to the war on drugs as president mirrored the same approach as when he was young.

"You f*** with my countrymen, I won't let you off the hook. Never mind about the human rights advocates."

Duterte also told the audience that if he met the United Nations rapporteur on extra judicial killings, Agnes Callamard, he would "slap her."

The estimated number of unlawful killings since Duterte won the presidency last year is 6000, including about 4000 by police.

Ardern said she would raise human rights in the same was that past leaders had - "That that level of death related to drug policy simply is not what New Zealand would expect to see as a national member of the international community."

Ardern attended a business breakfast in Manila on Tuesday where three MOUs were signed, covering continued co-operation between the New Zealand Government and the Philippinnes energy department on geothermal energy; promoting the Met office's forecasting expertise; and cooperation deal between Tourism New Zealand and Philippine Airlines about boosting two-way tourist numbers after direct flights begin in December.

Before the East Asia Summit forum began, Ardern had a bilateral meeting with India Prime Minister Narendra Modi at which the issue of Indian students was expected to be raised.

She also planned to invite him to New Zealand.