The 33 Chilean miners who have been trapped underground for three weeks have been told that they may not be rescued until the end of the year.
The health minister, Jaime Mañalich, said the men – who had not previously been told how long the operation could take – had accepted the news calmly during talks with the Chilean president, Sebastián Piñera.
"During a conversation with his excellency the president of the republic, we were pretty much able to tell them and they've accepted that they're not going to be rescued before Fiestas Patrias [Chile's independence day celebrations on 18 September]," said Mañalich last night.
"[But] we hope to be with them – and their families hope to be with them – before Christmas."
The minister added: "I think that we've been able to talk with them very frankly and they've accepted it and they're calm and they want to work well with us."
Mañalich said the men were still in good shape and revealed that rescue workers had managed to finish a second narrow borehole which would be dedicated to channelling drinking water to the miners and keeping communications flowing.
Rescuers are sending clothes, medicine and games down the 700-metre borehole, which has the diameter of a grapefruit, to help keep the men physically and mentally fit.
The government has asked Nasa and Chile's submarine fleet for tips on survival in extreme, confined conditions, and are intending to send them rations similar to those used on space missions.
Mañalich said the miners would also be given antidepressants.
"We expect that after the initial euphoria of being found, we will likely see a period of depression and anguish," he told reporters. "We are preparing medication for them. It would be naive to think they can keep their spirits up like this."
The miners have lost about 10kg each after having survived on half a glass of milk and two mouthfuls of canned tuna every 48 hours until supplies ran out. They have been told to watch their weight so they will be able to squeeze through the narrow escape shaft that is being drilled, and given tape measures to ensure they keep their waists below 90cm.
The men sent samples of water from underground tanks to the surface for testing, and rescuers are sending down fortified mineral water.
The miners are in good health, but officials are looking for ways to help ease the psychological pressure. They plan to set up special lighting in the tunnel to mimic night and day, with dull red lights to help the miners sleep.
Until now, the miners have used vehicle batteries to power lights and charge their helmet lamps.
The miners and their relatives are exchanging letters through the shaft.
"You have no idea how much my soul ached to have been underground and unable to tell you I was alive," Edison Pena said in a letter to his family. "The hardest thing is not being able to see you."
Esteban Rojas promised his wife he would finally buy her a wedding dress when he got out, and hold a church ceremony, 25 years after they wed in a registry office.
Officials are vetting letters sent by relatives, to avoid any shocks, although some disagree with the method.
"It's very important for the miners' mental health that they communicate openly with their families, and without filters, either by letter or by phone," said Claudio Barrales, a psychologist at the Universidad Central in Santiago.
The miners' relatives, who have been living in plastic tents at the minehead in a makeshift settlement dubbed Camp Hope, are gradually returning to their normal lives, but some are drawing up rosters so they can take turns at being at the mine.
The accident in the small gold and copper mine has turned a spotlight on mine safety in Chile, the world's top copper producer, although accidents are rare at big mines. President Piñera has fired officials of Chile's mining regulator and vowed to overhaul the agency.