WELLINGTON - New Zealand tourism and government officials are hoping the still-smoldering crater on a central North Island volcano that erupted last week will draw visitors from around the world after the government announced plans Tuesday to reopen hiking trails around the mountain.

The announcement came a day after the government's Institute of Geological and Nuclear Sciences (GNS Science) lowered the volcanic alert level for Mount Tongariro from level 2, warning of minor eruptive activity, to level 1, which indicated volcanic unrest.

A massive plume of ash billows up into the sky as Mount Tongariro erupts at Tongariro National Park, 300 km north of Wellington, in this Nov 21, 2012 file photo. [Photo/Agencies]

Tongariro's Te Maari crater erupted on Wednesday, sending a plume of ash and steam into the sky, but the ash had ceased and gas output had fallen, although minor seismic activity continued, said a statement from GNS Science.

"Over the next week, the scenario considered most likely is that there may be further eruptions and these could occur with no warning," it added.

On Tuesday, Conservation Minister Kate Wilkinson welcomed plans to reopen the Tongariro Northern Circuit and part of the Tongariro Alpine Crossing through the world heritage-listed Tongariro National Park on Thursday.

Tracks to the famous Emerald Lakes and Oturere Valley would also be opened on Thursday, Wilkinson said in a statement.

"The tracks planned for reopening can be used safely and give visitors spectacular scenes of the national park," she said.

"Tongariro National Park has over 1 million visitors a year and the Tongariro Alpine Crossing is New Zealand's most popular day walk. The reopening of tracks requires careful assessment by DOC (Department of Conservation) and GNS Science on the risk of any further volcanic activity."

The highest risk area within 1 km of the Upper Te Maari Crater remained closed.

Last week's eruption resulted in videos of panicked hikers fleeing from the plume, but DOC Ruapehu area manager Jonathan Maxwell said visitor safety in and around the park was paramount.

"The tracks being re-opened can not only be used safely, but will provide visitors with an amazing enhanced national park experience," Maxwell said in a statement.

"Tongariro National Park has world heritage status for its natural and cultural values. It is an active and living landscape and the recent events have left more exciting active features for people to view, film and photograph," he said.

"Volcanic landscapes around the world including Tongariro are first-class tourism venues attracting thousands of visitors each year. Tongariro with this recent activity may have just jumped up the worldwide must-do list, to perhaps the top."

Tourism Industry Association New Zealand (TIA) advocacy manager Geoff Ensor said the volcanic activity would add to the world- famous landscapes of the 80,000-ha park.

"This is a great opportunity to go out with experienced operators who know the area well and can point out the features of the new activity," Ensor said in a TIA statement.

Tongariro Alpine Crossing Transport and Guide concessionaires group (TACTAG) chairman Stewart Barclay said few other places in the world offered such a safe experience of an active volcano.

"The world famous Emerald Lakes, depicted in everyone's photographs of the Tongariro Alpine Crossing, are even more spectacular and vivid as a result of the recent volcanic activity, " Ensor said in the TIA statement.

Holiday Parks Association chief executive Fergus Brown said school groups would have an opportunity to experience an active volcano.

"We see a lot of school groups visiting the area at this time of year and did not want too many to have to cancel. What a great opportunity this is for them to study an active volcanic area," Brown said in the statement.

Tongariro's last previous eruption on August 6 was the first since 1897.