Speaking at a press briefing at around midnight, Narongsak also admitted that oxygen supply within the chamber where the 12 young footballers and their coach are sheltering has become a major concern.

Narongsak did not spell out specifically how the survivors would be taken out of the cave but hinted that they might have to dive their way out.  He said young soccer players have already started to learn how to dive.

The Weather Bureau has forecast heavy rains in the area in the next few days which means more water will flow into the cave, negating all the week-long efforts to drain flood waters out of it and posing more risks to the survivors.

The governor said the rescue teams are prepared to have the survivors sit it out in the cave for a longer period as long as the water level continues to recede.  But with more rains, there will be a pressing need for the survivors to be extracted.

“But whatever course of action we are going take must carry minimum risks,” he stressed, adding that whether or not the young survivors will have to dive their way out depends on their state of health and their readiness.

Narongsak was talking to reporters after an hours-long meeting of officials and rescue units concerned to review their options in dealing with the situation.

The governor said the level of oxygen in the cave, especially in the pocket where the survivors are sheltering, has become a matter of concern.  He said rescue units have installed an air chute to pump in additional oxygen while more oxygen cylinders were also brought in to provide more oxygen to the survivors.

He also said that another two British cave-diving experts were on their way to Thailand to help with the rescue mission.

Narongsak said the rescue teams still continue to explore alternative routes to get the survivors out of the cave.  They have drilled at more than 100 spots on the hillside and from the top of the  hill to explore possible points of entry into the cave.  But he said only 18 of the holes drilled have the potential of reaching where the survivors are.

But the governor admitted drilling through the solid rock to get to the target area would take a long period of time.  He cited the case of the famous rescue mission at a mine in Chile in 2010 which took rescue teams 2 months to bore a shaft to reach the trapped miners.