A New Zealand volcano, which had lain dormant for more than a century, has spewed rocks and ash over the centre of the country's North Island.

Mount Tongariro roared into life late on Monday night, as craters on the mountain exploded with flashes and booms.

The mountain, situated in Tongariro National Park, is a popular tourist attraction and can be seen in the Lord of the Rings films.

Nobody was injured in the eruption, but air traffic was disrupted.

Volcanologists said seismic activity in the area had increased in recent weeks and the spew of rocks, fine particles and steam from the snow-capped peak was caused by a pressure build up of volcanic gases.

The last time Mount Tongariro erupted was in 1897, ending a decades-long period of intermittent activity, and experts believe Monday's explosion could be the start of more such activity in the area.