MAE SAI, THAILAND (AFP) - Twelve boys and their football coach found alive in a Thai cave will be supplied with four months' worth of food and get diving training, the military said, as focus shifted to the tricky task of evacuating the group from the complex underground system.

The boys, aged between 11 and 16, were discovered with their 25-year-old coach late on Monday (July 2), rake thin but alive, huddled on a ledge deep inside a flooded cave nine days after they became trapped in a pitch black cave hemmed in by rising flood waters.

Much-needed food and medical supplies - including high-calorie gels and paracetamol - reached them on Tuesday as rescuers prepared for the possibility that they may be there for some time.

"(We will) prepare to send additional food to be sustained for at least four months and train all 13 to dive while continuing to drain the water," Navy Captain Anand Surawan said, according to a statement from Thailand's Armed Forces.

The miracle rescue sparked jubilation across the country after a gruelling operation beset with heavy downpours and fast-moving floods.

In total, more than 1,000 people have been involved in the operation, including teams from China, Myanmar, Laos and Australia. Rescuers include Thai navy divers, three top British cave divers and US military personnel.

"We called this mission impossible because it rained every day... but with our determination and equipment, we fought nature," Chiang Rai Governor Narongsak Osottanakorn said on Tuesday.

"The doctor advised that we should provide several kinds of medicine to prevent infection and other illnesses," said the governor, adding that medics had reached the young footballers.

The boys were found late on Monday by British divers, with footage showing them emaciated and huddled on a mud mound deep inside the cave.

They clearly want to leave. In footage that emerged after the boys were found by two British divers late Monday one asks to "go outside."

One of the diver replies "I know, I understand... no, not today."

Even if they are physically fit enough to dive, they will need the mental prowess to stay calm in the murky waters and claustrophobic passageways that stand between them and freedom. Fortunately, they seem in pretty good shape, considering.

"They're mentally stable which is actually pretty good," Belgian diver Ben Reymenants, owner of Blue Label Diving in Thailand who is assisting the search, told AFP.

"Luckily the coach had the sanity of mind to keep them all together, huddled together to conserve their energy, that basically saved them."

Here are the options rescuers might use to bring the boys out.

Diving

"The option to bring them out by diving is the quickest but it's also the most dangerous," Anmar Mirza, national co-ordinator of the US Cave Rescue Commission, told the BBC.

Skilled professional divers still needed several hours to get to the trapped group from the entrance, through tiny, debris-strewn passages and aided by round-the-clock water pumping efforts to try to clear the flood waters, the report said. And the young Thai boys are not trained divers.

Edd Sorenson, regional co-ordinator in Florida for the International Underwater Cave Rescue and Recovery Organisation, told the BBC the diving option is "extremely dangerous and hazardous", saying he would consider it "an absolute last resort".

"Having somebody in zero visibility that's not familiar with... that kind of extreme conditions, it's real easy and very likely that they would panic, and either kill themselves and/ or the rescuers."

Drilling

The authorities have tried to drill holes in the cave walls to help drain some of the flood water - although the thick rock has hampered efforts.

There have also been suggestions that drilling could be another way to get to the boys, and to help them out.

But to even begin the process, new roads would need to be built up above the caves to accommodate the heavy drilling equipment needed to break through the rock, reported the BBC.

On top of that, Mr Mirza explains to the broadcaster you would need to have conducted a survey of the caves and to know them back to front before you could start drilling - otherwise there would be little chance of digging a hole in the correct place for the boys and their coach.

"It sounds easy but it's actually very difficult," he says. "It's a needle in a haystack problem."

And, again, the boys need to spend time getting stronger in the depths of the cave before they can attempt to climb up a second entry - if one is found - or be lifted out.

Walk

This would be the safest option, but at the moment it is impossible because parts of the route remain flooded. So in theory they could wait, but that means hoping that flood waters subside.

Water pumps are working around the clock to drain the floods though it has been an uphill battle for much of the week as heavy rains refused to let up. If the current break in bad weather sticks, this option could be more promising.

But weather forecasters warn downpours may soon return as monsoon season sets in.

"If the rain fills up the cave system then that might take months before the water drops again," Belgian diver Ben Reymenants, owner of Blue Label Diving in Thailand who is assisting the search, told AFP.

Resupply?

In a press conference, Governor Narongsak said they would continue to drain water out of the cave while sending doctors and nurses in to check the health of the boys and their coach.

"If the doctors say their physical condition is strong enough to be moved, they will take them out from the cave," he said.

But Mr Mirza tells the BBC their health is a serious concern. "After nine days without food, you have to watch their food intake," he says.

People deprived of food can suffer ill-health effects if not properly reintroduced to food - sometimes as severe as heart failure or comas.

Mr Mirza says if the group are on high ground, safe from flooding, and can be resupplied there that might be a good option for now. Their ill-health "significantly compromises the rescue effort," he says.

Mr Sorenson agrees. "I think they would be better off bringing in food, water, filtration systems, oxygen if the air space needs it and requires it", he says according to the BBC.

"They have lights and hope now, so I think waiting it out, as long as they can get supplies in there to make them comfortable and warm and fed and hydrated."