A remote-controlled robot broke down after being sent down a New Zealand colliery where 29 men are missing, in a blow to rescue hopes, the local mayor said yesterday.

“We’ve had a kick in the guts, the robot went in the tunnel, it got water in it and short circuited, it’s history,” Grey District Mayor Tony Kokshoorn said after emerging from a meeting with rescue coordinators.

Frustration was rising among the families of 29 New Zealand men missing after a colliery explosion as rescue efforts remained stalled, the father of one of the miners said yesterday.

With the families’ agonising wait entering its fifth day, Laurie Drew said the patience of those with loved ones trapped in the Pike River mine was wearing thin.

“The grief, frustration and probably the anger will really start coming out if we get the same sort of information we have been given,” said Mr Drew, whose son Zen, 21, is among those who have not been heard from since Friday’s blast.

“We understand it’s a very slow process but it doesn’t comfort the grieving we have,” he told Radio New Zealand.

Rescuers have been unable to enter the mine in a remote part of New Zealand’s South Island because of the danger from a cocktail of toxic gases and a suspected fire underground.

Mr Drew said he did not understand why families were being kept at the town of Greymouth, 50 kilometres from the mine, rather than being allowed to stay close to where rescuers were on standby.

“It’s not as if we’d be running around every five minutes asking them ‘what are you doing?’,” he said.

“It’s just we’d rather be there, regardless of what way things eventuate, so that we’re on site if they walk out.”

Police have conceded that lives could have been lost following the explosion on Friday afternoon, which mining experts suspect was caused by a build-up of methane in the mine.