Mt Tongariro is showing more signs of unrest with tests showing the presence of volcanic gases.
A series of quakes beneath the mountain saw its alert status bumped up to level one on Friday.
GNS Science said while earthquake activity declined over the weekend, samples indicate volcanic gases are present and members of the public have reported gas smells.
While historic gas sampling has shown a mixture of volcanic and hydrothermal gases and fluids at Tongariro, sampling on Saturday showed a marked increase in the volcanic gas component, GNS Science said.
Mt Tongariro is a volcanic complex that lies to the north of Ngauruhoe. It consists of numerous craters and vents .
Ash eruptions have been recorded from Tongariro from 1855 to 1897, as well as unconfirmed activity in 1926-27.