A man has been rescued from dense bush in the Nelson Lakes after injuring himself tramping in thick snow.

The 59-year-old from Wellington was tramping with a group of people near Speargrass Hut in the Nelson Lakes National Park when he tripped and fractured his ankle this morning, the Nelson Marlborough Rescue Helicopter said.

The group activated an emergency locator beacon and Rescue Coordination Centre New Zealand dispatched the chopper around midday.

"Due to a very heavy overnight snow fall and dense bush, the location of the group was made extremely difficult for an aerial search," the Nelson Marlborough Rescue Helicopter said.

Once the crew found the group, an onboard intensive care paramedic was winched into the bush where the man was stabilised and winched out.

He was then flown to Nelson Hospital emergency department for further assessment.