The victims of the blasts ranged from a 17-year-old on his first shift to a 62-year-old veteran [AFP]

All 29 miners trapped in a coal mine in New Zealand have been presumed dead after a "horrific" second blast tore through the colliery, plunging the country into mourning.

Police said there was now no chance of finding anyone alive, confirming the country's worst mining accident in nearly a century and prompting anguished scenes as distraught relatives wept, shouted  and collapsed to the floor.

"We are a nation in mourning"

John Key,
Prime Minister of
New Zealand

"There was another explosion at the [Pike River Coal] mine. It was extremely severe," Gary Knowles, the police official co-ordinating the rescue attempt, told reporters.
  
"Based on expert evidence I have been given ... it is our belief that no one has survived and everyone has perished."
  
Knowles said the explosion, whose cause was unknown, ripped through the Pike River coal mine at 2:37pm local time, (0137 GMT), on Wednesday, five days after the initial blast trapped the 29 men including 24 New Zealanders, two Australians, two Britons and a South African.
  
The victims of the blasts ranged from a 17-year-old on his first shift to a 62-year-old veteran.

'Lethal mixture'
  
High levels of toxic and combustible gases had stopped rescuers entering the mine in a remote area of New Zealand's South Island.

"I was at the mine myself when this actually occurred and the blast was horrific, just as severe as the first blast and we're currently now moving into recovery phase," Knowles said.

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

Tony Kokshoorn, the district mayor, said the incident was the "darkest hour" of New Zealand's rugged West Coast region, a centre of the country's burgeoning mining industry based on exports to Asia.
  
"It's unbelievable. This is the West Coast's darkest hour. It doesn't get worse than this," Kokshoorn said.
  
He added that grief-stricken families, who have suffered an agonising five-day wait for a rescue that never came, were angry that the dangerous gases had been allowed to build up again.
  
"They don't know what to do. They just sobbed openly, just fell  to the floor. There were people just shouting out, anger," Kokshoorn said.
  
"The cause was the build-up over the last five days of the gases again and they noticed that this morning. A lethal mixture ignited the entire mine," he added.

John Key, New Zealand's prime minister, called the disaster at Pike River "a national tragedy".

He said: "To lose this many brothers at once strikes an agonising blow. We are a nation in mourning."

Investigation launched

Key said an inquiry would investigate how and why the accident had happened.
  
Gerry Brownlee, New Zealand's energy minister, announced a series of inquiries aimed at finding out the cause of the mine disaster and preventing any repeat.
  
New Zealand lost 19 miners in 1967 but the last accident on this scale was in 1914, when 43 died in a gas explosion at a mine in Huntly on New Zealand's North Island.

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.
  
Stop-start rescue efforts had earlier inched forward when a bore hole into the mine finally broke through, revealing a toxic cocktail of dangerous gases with little oxygen.
  
A remote-controlled robot - the second such device after an earlier one broke down - also travelled about a kilometre into the mine.

Source: Agencies