At least 11 illegal miners are reported to have died, following the collapse of an open mine in an area in Mozambique's northern Cabo Delgado province.

Work to rescue the buried bodies is still under way, Cabo Delgado's provincial director of mineral resources and energy, Ramiro Guilaze, says.

Mr Guilaze says, so far, 13 of the buried people were rescued, two of them still alive.

He says it is believed that there were 15 people in the mine before it collapsed.

Mr Nguilaze said the mine collapse occurred at an area close to the Montepuez Ruby Mining or MRM, a subsidiary of the London-based Gemfields group, which used its machinery to assist in rescue operations.

In a statement, the mining company blamed the authorities' inaction against the illicit trade of rubies.

In northern Mozambique, informal and illegal ruby mining is a competitive business that has attracted thousands of itinerant workers despite strenuous crackdowns by the authorities.

This is not the first time that illegal miners die in landslides not only in Cabo Delgado but also in Manica province in their attempts to pan either for gold or rubies.