The collapse of a small-scale illegal gold mine killed at least 22 people in northern Tanzania after heavy rains, a senior government official said on Sunday.

The accident happened on Saturday morning in the Simiyu region, after a group of people aged between 24 and 38 began mining in an area where activity had been restricted due to heavy rains, Simon Simalenga, the region's Bariadi district commissioner, told Reuters.

"Initially we were informed that there were 19 to 20 people trapped in the mines, but unfortunately we ended up recovering 22 bodies," he said, adding that the search and rescue operation was continuing, although almost all the rubble that buried them had now been removed.

Simalenga said that the group discovered an area rich in minerals about two to three weeks earlier and started mining before the government had approved procedures and physical and environmental security.

"The regional mining officer visited them and prevented them from mining while he worked through the required procedures," he said.

The group defied the order, he added, starting to mine on Friday night, before part of the area collapsed and buried them inside.

The government has been working for years to improve the safety of small-scale miners, but illegal, unsafe and unregulated mining still takes place in Tanzania, which is Africa's fourth largest gold producer after South Africa, Ghana and Mali. (Text: Reuters)