Families of the four boys who were rescued on Sunday evening have not yet seen them since they were rushed to the Chiangrai Prachanukroh hospital, about 60 miles from the cave.
Narongsak also said Monday that the condition of the five remaining people in the cave is "still good". "But they still need to be kept away from their parents and others due to fear about infection", he said. The four boys survived the treacherous journey through the Tham Luang caves, all emerging to walk unscathed into the hands of waiting medics.
Nine people remained trapped in the cave, including the team's coach, after four boys were rescued on Sunday, the first day of the rescue operation.
But the efforts to rescue the boys - aged between 11 and 16 - have proved a monumental challenge. Some stretches of the Tham Luang cave are more than 10m (33ft) high, while others are a tight squeeze through water-filled passages.
The global effort to save the group has paired divers in "buddy teams" with the remaining eight boys and their coach. It could take two to four days complete the mission, officials said.
For the final operation tomorrow, Mr Narongsak said the rescuers would use the same plan with some adjustments because the number of survivors to be extracted would be five instead of four as was the case for the last two days.
The boys who were rescued on Sunday were strong and safe but needed to undergo detailed medical checks, he said.
James Massola, on the ground in Chiang Rai province, covered the press conference after the rescue was wrapped up for the night, and reported that rescue mission chief Narongsak Osotanakorn said the team was "getting used to the operation".
Ambulances transport boys rescued from Tham Luang Nang Non cave to hospital on July 8, 2018 in Chiang Rai, Thailand.
In comments released by the government, Interior Minister Anupong Paojinda said the same divers who took part in Sunday's rescue will also conduct the next operation as they know the cave conditions and what to do.
The Thai youth soccer team and their coach became trapped in the cave they were exploring on June 23 after heavy rains flooded exits.
Each boy is being accompanied by two divers and it takes several hours to negotiate the flooded tunnels through the dark, murky water.
Around 20 Australians have been involved in rescue efforts to free 12 boys and their soccer coach from a Thai cave.
But with oxygen levels inside dropping to risky lows and the prospect of heavy rains flooding the area completely, authorities decided they had to move quickly, and take the group out through the water-filled tunnels.
After the four boys were removed from the cave, heavy rain started falling.
Rescuers have been navigating a unsafe and complicated plan to get the children out under the threat of heavy rain and rising water underground. An international-level rescue mission began soon after, with hundreds of experts and military personnel from various countries arriving at the spot.
The other, and perhaps more worrying, was that oxygen levels in the complex were falling close to risky levels.