White Island volcano off the Bay of Plenty has erupted with an increase in volcanic gas levels and tremors.
GNS Science released a statement on Monday evening saying cameras had captured photographs of a small eruption that occurred about 5am on Sunday at Crater Lake on the island.
The alert level has since been raised from one to two on a scale of zero-five. White Island consistently sits on alert level one.
During the past fortnight there has been an increase in volcanic tremors, volcanic gas levels and the crater lake water level rose 3m to 5m.
"These phenomena are not unknown for White Island, but this is the first substantial confirmation that small scale eruptions are now occurring on the island and confirms the risk to visitors has increased," GNS Science said.
"Eruptions can occur at any time with little or no warning. We advise extra caution should be taken if visiting the island."
The volcano is estimated to be between 150,000 to 200,000 years old and was named White Island by Captain Cook in 1769.
In Maoridom it is known as Whakaari which means "that which can be made visible".
Sulphur mining was attempted on the island from 1885 until 1914, when a lahar destroyed the sulphur mine, mine village and killed 12 people. Mining resumed in the 1920s but the mining company went bankrupt in the 1930s.
The main activities on the island now are guided tours and scientific research.