Britons still trapped in NZ mine

Several Britons are among the 29 men trapped in a remote New Zealand coal mine following an underground explosion.

Fears over gas levels and a risk of a second explosion are delaying rescue efforts with officials waiting until they feel it is safe to enter the country's biggest underground coal mine.

Anguished relatives voiced frustration a day after a powerful blast left the workers missing underground.

"If I had my way I'd be down there, I'd go into the mine myself," said Laurie Drew, whose 21-year-old son, Zen, is one of the missing men.

Rescue organisers said the level of methane and carbon monoxide was still too high to send a crew into the Pike River Mine.

Two miners reached the surface after Friday's gas explosion, but there has been no word from 29 others. A working telephone line at the bottom has still not been answered.

Superintendent Gary Knowles from New Zealand Police tried to reasure those that were worried.

"I am not going to give a percentage or the feeling in my gut. We work on facts. When the time is right and we are comfortable to say that it's safe, we'll be going in and we will keep the families up to date all the way through the process and they know - like we do - they don't want their colleagues to go underground if it's a risk for them as well."