More than 30 gold miners have died in an informal pit in the Democratic Republic of Congo's South Kivu province after a landslide, officials said Thursday, with dozens more feared trapped.

The incident happened a week ago in Misisi in the Fizi region.

"There has been an accident in a gold mine in Misisi. Proper searches only began today," said Aime Mutipula, the area's top local official, without giving a toll.

"At least 37 people have died according to a provisional toll," said Tyber Kajemba from the Governance and Peace Observatory, a non-governmental organisation which specialises in mining activities in the area.

He said others were trapped "between 70 and 80 metres" underground and added that the mine was "poorly maintained".

Deogratias Musafiri, a civil society leader from Fizi said: "The provisional toll is 32 dead. That's the number of bodies we have brought out this afternoon."

Heavy rains have been lashing the area. Mining accidents are common in DR Congo and rescue operations are often slow and patchy.