There are fears the number of missing following a deadly landslide in Papua New Guinea could stretch into the thousands, a government agency has said.

The acting director of the nation's National Disaster Centre said in a letter it was feared more than 2,000 people were buried alive in Friday's disaster.

However, an exact casualty figure has been hard to establish and estimates have varied widely, as rescue efforts have been hindered by rubble 10m deep in some places and a lack of adequate equipment.

Fewer than a dozen bodies have been recovered so far, while the United Nations put the figure of the missing at 670.

The collapse of a mountain side early Friday morning wiped out a bustling village in Enga province, where about 3,800 people had been living.