An engineer assisting in the rescue says Tuesday's collapse will delay the removal of dirt and rock from the horizontal shaft dug into a mountainside where the men were trapped by an explosion they set.
Ana Jara, Peru's women's affairs minister, had earlier said that authorities expected to free the nine on Tuesday night. They range in age from 23 to 58 years.
Among nervous relatives waiting outside the mine was Celestina Lopez, whose husband and two sons were among the trapped.
Jara says some miners have stomach infections. They have been administered liquids and medicine through a hose that also lets them talk with people outside.
'Metres away'
The miners have been trapped in a horizontal tunnel since Thursday when a shaft collapsed in Cabeza de Negro mine.
"Today will be key, they [rescuers] are only three metres away", from the trapped mine workers, said Jara, speaking to reporters at the scene before the small collapse.
Workers specializing in reinforcing tunnels arrived Monday to shore up shafts at the collapsed copper mine.
Rescue officials said they were able to communicate overnight with the miners, providing hope of a happy outcome to the ordeal.
The rescue effort was being aided by 20 specialists from private mining companies.
The Peruvian miners' fate recalled a similar case in Chile that made world headlines.
In August 2010, 33 miners were trapped in a cave-in in the San Jose gold and copper mine in northern Chile. After 69 days and a spectacular rescue operation with the world watching, they were brought out safely.
