Soldiers trying to retrieve bodies after volcanic eruption. (AFP PHOTO/ NEW ZEALAND DEFENCE FORCE)

Divers searched seas around New Zealand's volatile White Island Saturday for two people still missing five days after the volcano erupted, amid warnings it could do so again.

Police deputy commissioner John Tims said the divers faced "unique and challenging conditions" as they searched waters "with between zero and two metres visibility".

They were focusing on an area where a body was seen floating in the water earlier in the week.

Prime Minister Jacinda Ardern, meanwhile, has called for a minute's silence to be observed at 2.11pm (0111 GMT) on Monday in honour of the victims of the eruption.

"Together we can express our sorrow for those who have died and been hurt, and our support for their grieving families and friends," Ardern said with the minute's silence to start exactly one week after the eruption began.

Of the 47 people on the island at the time of the eruption, at least 16 were killed while 28 remain in hospitals in New Zealand and Australia with 21 listed as being in a "critical" condition.

Scientists monitoring the island said the likelihood of another eruption over the weekend was decreasing but the risk remained.

"Their new calculation was that there is a 35-50 per percent chance of an eruption occurring," Natalia Deligne, a volcanic hazard and risk modeller, said.

The remains of six people were retrieved Friday in a daring rescue by elite soldiers under threat of another blast.

Most of the people on the island were tourists from Australia, the United States, Britain, China, Germany, Malaysia and New Zealand who were on a day trip to see the natural wonder.