Mozambique police said Thursday at least a dozen people were trapped underground after an illegal mine collapsed in the northern district of Memba, killing five miners.

"Five people have died and so far 20 people have been rescued," police spokesman for Nampula province, Miguel Bartolomeu, told AFP on Thursday.

An estimated 40 illegal gold miners were believed to have been in a 12-meter deep opencast mine when it collapsed on Tuesday, in the district of Memba near the border with Tanzania.

"They have been underground for three days and we do not know if they are alive," Bartolomeu said.

The rescue effort had been conducted in an "archaic fashion" without the basic equipment needed for the operation, according to a local newspaper, O Pais.

"Until yesterday morning (Wednesday), voices could be heard calling for help but by the end of the day they had fallen silent," the paper said.

Provincial authorities had sent fire fighters and police to aid in the rescue effort.

Illegal miners, known in Mozambique as "garimpeiros," had begun flocking to Memba after gold was discovered there six weeks ago.

Besides vast coal and natural gas deposits, the sub-Saharan African country also has mineral deposits including gold, diamonds, titanium and precious stones.