Health Minister Jaime Manalich said five of the 33 miners, trapped 700m (2,300ft) below ground, were not eating properly and had refused to be filmed.

Mr Manalich said psychologists would attempt to treat the men from the surface over an intercom system.

Engineers say work on an escape tunnel, which may take four months to reach the miners, will have started by August 30.

The men, who have already been stuck in the shaft for three weeks, were only discovered on 22 August.