Three avalanches on Mt Ruapehu have closed part of the Turoa ski field but no-one was caught by the snowslips.

Mountain manager Chris Thrupp told NZ Newswire a natural avalanche near the mountain's summit came down at about 2.15pm on Sunday, towards the western boundary of the ski area.

Police say there were three avalanches in total by about 3pm.

The avalanches are believed to have been caused by warm temperatures which stopped fresh snow that fell last week bonding to old snow underneath.

No-one was near the area at the time but there were concerns about a further avalanche risk above the ski area, Mr Thrupp said.

Turoa has closed its upper mountain lifts and brought skiers down to lower levels on the mountain.

"There's no risk at the lower level. It's just above the ski area in some of the upper mountain slopes, potentially, but nothing has come down into those," Mr Thrupp said.

A group of about 35 people was hiking through a high-risk area above the ski boundary towards Mt Ruapehu's summit, and patrollers had been sent after the group to turn them around.

Ruapehu Alpine Rescue had also been put on standby, Mr Thrupp said.

"They're just out of earshot, so we yelled at them but they couldn't hear, so these guys are taking a safe route, walking up the ridge parallel to them, and telling them to turn back," he said.