Rescue efforts to save 33 trapped miners face a setback after a drill struck an iron support beam for a mine shaft at about 300m, destroying the drill bit.

Mining minister Laurence Golborne said the setback is within the range of problems foreseen by authorities before the rescue began, and does not significantly alter the expected timeline for rescuing the miners.

Meanwhile, a second drill that stopped working on 10 September for routine maintenance resumed operations the following day, reports The Associated Press.

The Plan C tunnel, the fastest of the three tunnels, and capable of reaching the miners in 45 days once it comes online, is being set up and will be nearly 45m long when assembled.

Multiple narrow bore-holes have been opened up to pass food, water, oxygen, electricity and messages to the miners, who remain trapped at 688m after a main shaft at the San Jose copper mine collapsed on 5 August.