WELLINGTON: A New Zealand volcano dormant since 1897 has spread boulders and an ash cloud over the centre of the country, disrupting air traffic but causing no other damage.

Mount Tongariro, one of three volcanic peaks in the centre of the North Island, roared into life late on Monday.

Volcanologists said the spew of rocks and steam from the 6490ft peak was caused by a pressure build-up of gases after seismic activity had increased.

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