LIMA, Peru - It may take two or three more days to rescue nine miners trapped in an informal copper mine, Peru's prime minister said, as rescuers supplied the men with liquid sustenance through a hose.

The miners have been stuck since Thursday, when a shaft collapsed following a blast apparently set by the men themselves inside the mine, which is dug into a mountainside 280 kilometres southeast of Lima.

Dozens of rescue workers have been using pickaxes and shovels to try to remove the eight meters of collapsed earth and rock blocking the entrance of the mine.

Local police chief, Jose Saavedra, told The Associated Press that several tons of earth and rock have already been removed from the tunnel's mouth, but Mining Minister Jorge Merino appealed for mining companies to provide heavy equipment and experts to speed up the effort.

On Sunday evening, miners arrived from two nearby mines to help dig out the workers.

Through a hose, rescuers have been able to communicate with the men and send them liquids.

Prime Minister Oscar Valdes, who said that he had spoken to the miners, told reporters that he estimated it would take to three days to free the men. The miners' health appears to be fine.

Officials worry, however, that some could suffer from exposure.

"They're being subjected to a lot of cold. The temperature is low because of the humidity," Valdes said.

The appearance of Valdes and Merino at the Cabeza de Negro mine 1,347 metres above sea level highlighted what some consider the government's lack of preparation for such an accident.

Peru "doesn't have a specialize team for mining rescues," said Jose de Echave, a former deputy environment minister.

Mining is the main engine of Peru's economy, accounting for more than 60 per cent of its exports. It is the world's No. 2 copper exporter after neighbouring Chile and ranks sixth in gold exports.

According to official figures, 52 miners died in Peru last year in work-related accidents, a third of them in mine shaft collapses.