Police Superintendent Gary Knowles said during a news conference conditions remained too dangerous for rescue crews to enter the mine near Greymouth because of possible heating underground, The (Wellington) Dominion Post reported Monday.
"We still remain optimistic, we are still keeping an open mind, but we are planning for all outcomes and ... also under this process we are planning for the possible loss of life as a result of what has occurred underground" in Friday's explosion, Knowles said.
Rescuers had to establish "beyond reasonable doubt that an emission source does not exist," Knowles said. "For this reason we in the process ... [of] establishing another sample point through another bore hole. "
Knowles said no rescue attempt would be undertaken Monday, explaining the environment was too dangerous, the newspaper said. An army robot was being prepared to be sent into the mine, but rescue officials said they wouldn't lower anything underground until they were sure sparks wouldn't touch off another explosion.
New Zealand Prime Minister John Key indicated an inquiry would begin after the crisis is over.
"It is a highly, highly irregular event that has taken place and we'll need to understand what the cause of that is," Key said. "There will be an inquiry, if not inquiries, into what has taken place at Pike River. ... We need to understand better what's gone on and why, and in due course, we'll seek to find those answers."