New Zealand mine: Fears grow for trapped UK miners
Fears are growing for two Britons among the 29 men missing after an explosion in a New Zealand coal mine, as rescuers remain unable to enter.
Peter Rodger, 40, and Malcolm Campbell, 25, are from Scotland, the Foreign Office confirmed.
David Cameron and Prince William have both contacted New Zealand's Prime Minister John Key to offer support.
A new exploratory hole will be drilled at the West Coast's Pike River mine on Sunday, to further test gas levels.
Pike River Mine Chief Executive Peter Whittall said the latest tests had shown there was still heat being given off underground. Carbon dioxide, methane and other dangerous gases were still being generated but there was no evidence of a big fire, he said.
Rescuers say they have no idea how long it might take to reach the men.
Mr Rodger, a former Perth Grammar pupil, emigrated to New Zealand two years ago to be closer to his mother and sister who live there, according to the Courier newspaper.
He was formerly an offshore oil engineer.
Gary Fraser, a friend of Mr Rodger, told the BBC he was a "strong character" and that this was the second time he had been trapped in recent months.
The parents of Mr Campbell, from St Andrews in Fife, said they had to keep hoping for good news.
In an interview broadcast on STV News, his father Malcolm said: "We can't concentrate on anything, we can't sleep because it's difficult.
"Our prayers and thoughts go out to everybody who is going through this in New Zealand. We just keep hoping that everything will be fine."
The miner is due to marry his fiancee, Amanda Shields, 23, on 18 December.
There has been no contact with the miners since an explosion around 1530 local time (0230 GMT) on Friday.
A Foreign Office spokesman said both the UK miners are residents in New Zealand and their families had been offered consular assistance.
Prince William's message came in the form of an email.
A Clarence House spokesman explained: "William has been to New Zealand on several occasions and is very fond of the country. He wanted to send a message of support."
Prime Minister David Cameron, who is in Lisbon for the Nato summit, is being kept informed of developments, Downing Street said.
"Clearly he is deeply concerned about the appalling situation there. Clearly we stand ready to provide any assistance that is required," a spokeswoman said.
The prime minister has sent a text message to his New Zealand counterpart John Key, which read: "I am thinking and praying for the best. I will make sure our diplomatic team help in any way they can".
Foreign Secretary William Hague said the British high commission in New Zealand was working with the New Zealand authorities to help to contact relatives locally and in the UK.
"It is a very worrying situation and we will do our utmost to assist," he told Sky News.
Pike River Mine Chief Executive Peter Whittall told a news conference on Sunday the latest tests had shown there was still heat being given off underground.
Carbon dioxide and methane were still being detected but there was a downward trend in gases and no evidence of a big fire.
The missing workers range in age from a 17-year-old - believed to be on his first shift - to a 62-year-old.
Each miner carried 30 minutes of oxygen, enough to reach oxygen stores in the mine that would allow them to survive for several days, officials from Pike River Coal, the mine operator, said.
Andrew Watson of the Mines Rescue Service, in the UK, said rescue efforts would be frustrated by fears for the safety of the rescuers themselves.
He said the trapped men would have been "trained to barricade themselves into somewhere where they are safe".
To let rescuers know they are still alive, he said the best way would be to "hit solid strata". Above ground a listening device, called a geophone, would detect that signal, he said.
The natural hazards associated with coal mining include the build-up of methane and the risk of spontaneous combustion.
With an explosion inside a mine, transport, communication, ventilation and the means to monitor conditions inside the mine would be disrupted or lost, Mr Watson said.
This means monitoring is restricted to very close to the mine surface. "They won't have enough confidence in the information they're getting to deploy the [rescue] teams," he said.
The mine, which employs some 150 people, has been operational since 2008 and runs deep under the Paparoa Ranges on the rugged western coast of the South Island.
The missing include 24 New Zealanders, two Australians, two Britons and a South African national.
An electrician went into the mine at 1550 local time to investigate a power failure, and 1,500m (4,920ft) into the shaft he discovered the driver of a loader who had been blown off his machine. He then raised the alarm.
Mining experts said it could have been an explosion of methane gas, coal dust, or a combination of the two.