The Department of Conservation (DOC) is warning of increased signs of volcanic activity at Mt Ruapehu.
DOC issued a statement this afternoon advising climbers and other visitors considering visiting the summit area of Mt Ruapehu that there may be an increased chance of eruptions from Crater Lake.
"Risks to people entering the Summit Hazard Zone within about 2km of Crater Lake are assessed to be higher than normal. Gas concentrations near the lake have increased to levels that will affect some people."
GNS scientists have continued to monitor the activity at Ruapehu since the moderate-sized eruption in September last year.
No further eruptions had occurred, but an increase in gas output and the internal temperature of the volcano represent "an anomalous state of activity".
DOC said it was unclear whether this was a sign of further eruptions in the near future but if there were they may occur without warning.
The alert level remains at Level One.
GNS Science will continue to re-assess the situation regularly.