At least 40 people were killed after a tunnel collapsed in a gold mine in Mali, officials say.

"It started with a noise. The earth started to shake," Oumar Sidibe, a local official for gold miners told the AFP news agency.

The tunnel collapsed at a site in the south-western Koulikoro region on Friday but the number of deaths had not been reported until now.

AFP quotes officials as saying that more than 70 people died.

Mr Sidibe said: "There were over 200 gold miners in the field. The search is over now. We've found 73 bodies."

Mining ministry spokesperson Baye Coulibaly told Reuters news agency the provisional death toll was more than 40.

Mali's government expressed "deepest condolences to the grieving families and to the Malian people".

It also asked communities living near mining sites to adhere to safety requirements and to only work in areas reserved for gold panning.

Mining accidents are common in the country as most unregulated miners use unsafe methods to dig for gold.

Mr Coulibaly said the ministry had strongly advised miners against digging unauthorised tunnels, but that it had been "in vain".

The ministry said they would investigate the incident further and send a team to the area on Thursday.

Mali is one of the world's biggest exporters of gold.