Even though the mine is a hydro-mining operation, which uses high-pressure water to cut the coal, it appears the risk assessments for the robot did not ensure it was waterproof.

The robot entered the mine at 6am and travelled about 550 metres before it got too wet and faltered.

Tasman area police commander, superintendent Gary Knowles told a media conference he heard the robot had broken down at 8am.

Video might be released from the robot’s failed journey, but it is expected to only show a clear tunnel.

Knowles revealed that rescuers might try to get more advanced robots from Western Australia and the US.

Using a robot avoids risking more lives as off-the-chart flammable gas readings indicate a secondary explosion could still occur in the mine.

While rescuers worked on securing a longer control cable to make sure the robot could travel along the 2.2-kilometre tunnel to the area of first workings yesterday, the idea of using a robot received scientific criticism.

University of Queensland associate professor at the Minerals Industry Safety and Health Centre David Cliff and New South Wales Mines Rescue general manager Paul Healey were both sceptical.

“Robots in general in the past have seldom worked; they are not able to cope with the level of damage found in the mines and are not flame-proof or intrinsically safe,” Cliff said.

He added that a robot had been deployed after the Sago mine explosion in West Virginia in 2006, but with “limited success”

"They cannot be used in flammable atmospheres. They usually trail a cable for control and communications and these are prone to damage.”

Cliff said Queensland’s Safety in Mines Testing and Research Station had a robot with cameras, gas monitoring and temperature sensing.

“NUMBAT is the most famous Australian robot which never achieved its potential – it cost millions of dollars but needed much more to make it really useful."

Healey was not confident about a robot’s chances at Pike River.

“The use of robotics for mine recovery has been talked about for many years but at this stage nothing has been developed which is practical for use in extended operations, and the mine roadways are generally not like highways and robots have difficulty travelling on rough terrain,” he told ABC Radio.

Three experienced gas analysis chemists from SIMTARS are already at the scene along with experienced Australian mine rescue personnel.

Australian Prime Minister Julia Gillard told Parliament yesterday that Rio Tinto, BHP Billiton and Xstrata had placed staff and resources “at the ready should they be required”.

“We want nothing more than to see these 29 men brought to the surface safe and well,” she said.

“This is a hope that unites us and unites the world today.”

Even though the missing miners are expected to make their own way out of the mine using self-rescuers under the mine’s safety procedures, Knowles was less optimistic this morning that there could be survivors.

“This is a very serious situation and the longer it goes on, hopes fade and we have to be realistic,'' he was reported as saying in The Australian.