There had been no contact with the men since Friday's methane-fuelled explosion [GALLO/GETTY]

All 29 miners trapped in a coal mine in New Zealand are believed to be dead, according to police.

Wednesday's statement came after a second explosion rocked the Pike River Coal mine.
  
"There was another explosion at the mine. It was extremely severe," Gary Knowles, the police official co-ordinating the rescue, said.
  
"Based on expert evidence I have been given ... it is our belief that no one has survived and everyone has perished."

There had been no contact with the men - 24 New Zealanders, two Australians, two Britons and a South African - since an explosion on Friday.

'High gas levels'

On Tuesday when rescue workers drilled into the mine, they discovered high gas levels and little oxygen near where the miners were believed to be.

As a result, Knowles told reporters that it was "not safe to send rescue teams down".

Officials said air coming from the drill hole showed high levels of carbon monoxide and methane and was low on oxygen, which meant that sending down rescuers could trigger an explosion.

A robot had also been sent down the shaft of the Pike River mine on the west coast of the South Island to check the tunnel and toxic gas levels after Friday's methane-fuelled explosion.

The release of security camera footage showed the result of the blast's power and lowered expectations of the mens' survival.

The youngest of the 29 miners was on his first day on the job, just a day after his 17th birthday. Joseph Dunbar was so excited he persuaded mine bosses to let him start his first shift three days early, Philippa Timms, his mother, told media.

New Zealand's mines have a solid safety record, with 181 deaths in the country's mines in 114 years. The worst disaster was in 1896, when 65 died in a gas explosion. Friday's explosion occurred in the same coal seam.

Source: Agencies