Another eight people including another child were injured yesterday as the avalanche buried about 10 houses.
"The child died during the day," a spokeswoman of the regional university hospital told the NTB news agency, without stating the child's age or gender.
A 42-year-old man died in the disaster yesterday in the foothills of Mount Sukkertoppen overlooking Longyearbyen, the archipelago's remote capital where coal mining families and polar bears live side by side.
The avalanche buried around 10 of the brightly coloured wooden houses that are typical of the archipelago.
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Witnesses said the snow had shifted some houses about 20 metres.
The governor ordered the evacuation of 180 people living at the foot of Sukkertoppen (Sugar Mountain).
Emergency accommodation has been set up in a youth centre and the town's church.
Weather conditions have been harsh since Friday with high winds.
Longyearbyen is the world's most northerly town, situated about half-way between continental Norway and the North Pole.