The miners have been able to send video messages and talk to their families by radio-telephone [Reuters]

Rescue workers in Chile are set to begin the long task of drilling a shaft to rescue the 33 miners who have been trapped deep underground for more than three weeks.

The stranded men have been asked to move hundreds of tonnes of rock themselves as a part of the rescue operation that could take several months.

Meanwhile, officials were pushing for an accelerated rescue plan, and Sebastian Piners, the president, said he wanted to get the miners out before September 18, the bicentennial anniversary of Chile's independence from Spanish colonial rule.

Another plan "has already been designed", Jaime Manalich, the health minister, said. Details would be released soon, he said.

Under the current plans, an hydraulic bore will begin drilling a hole 66cm wide on Monday, aimed at pulling the miners out one at a time from the hot and damp shelter where they are huddled underground.

"The shaft we're drilling to the shelter will go down 702m in a straight line [to the trapped miners]”, Andre Sougarret, the engineer in charge of the rescue operation, told AFP news agency on Saturday.

He said the drilling operation was expected to last three to four months, as the hydraulic bore drills at a maximum rate of 20m per day.

Tons of debris

The drilling is expected to cause rock to fall down into the mine shaft area near the trapped men, and failure to keep the bottom clear of debris could quickly plug the hole, delaying the rescue.

Therefore, the trapped miners will have to clear tons of rock, a requiring them to work in shifts all through the rescue.

Officials are also considering drilling where the main entrance ramp to the San Jose gold and silver mine collapsed on August 5, though some engineers fear the site remains unstable.

A third option being tabled suggests broadening an already existing shaft, about 300 metres from the emergency shelter where the miners are confined.

However, Laurence Golborne, the mining minister, denied reports of a possible rescue within the next month.

"We have reviewed 10 different options," he told Radio Cooperativa.

"Up to now there is no alternative ... that would allow us to get them out in 30 days."

The trapped miners spoke for the first time with their loved ones Sunday, reassuring each other in brief conversations by radio-telephone.

"To hear his voice was a balm to my heart," Jessica Chille said after speaking to her husband, Dario Segovia.

Limited to one minute per miner, the wives, mothers and fathers lined up for their first person-to-person conversations since a cave-in on August 5 that blocked the miners' exit from the San Jose gold and copper mine.

'Excellent odds'

Peter McCarthy, a mining expert in Australia, said the heat and humidity in the mine could put the miners' health at risk but said the odds of them being rescued alive were "excellent".

"My understanding of the situation is that there's a large space there for them," he told Al Jazeera.

"They have hundreds of metres, if not kilometres, of tunnels they can move through and with the connection of three large bore holes down to them, air, supplies and communications can be maintained."

While most of the miners appear to be in good spirits, a handful of them seem to be struggling psychologically.

Jaime Manalich, the health minister, said five depressed miners were in a better state of mind after receiving food, vitamins and communicating with friends and relatives, who sent them a video recording earlier Saturday.

Chilean authorities have already taken steps to improve the men's mental resilience for the wait that lays ahead, especially by reaching out to organisations and individuals with experience in long isolation.

Four officials from the US space agency Nasa were due to arrive in Chille on Monday to provide expertise, while submarine commanders in Chile's navy have already given advice.

Source: Al Jazeera and agencies