Around 30 people were killed at a semi-industrial copper mine in southeastern Congo on Saturday after a bridge collapsed, the country's artisanal mining agency said.

An agency official told Reuters there were 49 deaths and 20 people had been taken to the hospital in a critical condition as a result of the incident, which occurred on Saturday at the Kalando mining site in Lualaba province.

Artisanal mining employs an estimated 1.5 to 2 million people in Congo and supports more than 10 million indirectly.

The collapse was "caused by panic, reportedly triggered by gunfire from military personnel securing the site," said Congo's Artisanal and Small-Scale Mining Support and Guidance Service, known by its French acronym SAEMAPE.

Miners then "piled on top of each other, causing injuries and death", SAEMAPE added in a statement on Sunday.

The Initiative for the Protection of Human Rights called for an independent investigation into the military's role in the deaths, citing reports of clashes between miners and soldiers.

A military spokesperson did not immediately respond to a request for comment.

Roy Kaumba, the provincial interior minister, said in a televised statement that 32 people had been confirmed dead.

Mining accidents are common in unregulated artisanal mines, with dozens of deaths every year at sites where often ill-equipped diggers burrow deep underground.