Copiapo, Chile (CNN) -- Officials working to free 33 trapped miners in northern Chile denied Thursday they are under political orders to rescue the men ahead of President Sebastian Pinera's planned mid-month trip to Europe.
"No decision about any part of the rescue operation has been linked to any political decision. The miners' health and technical decisions come first," Interior Minister official Cristian Barra said in a news conference at the San Jose gold and copper mine.
"The president's agenda is not connected to the timeline for rescue. There are no guarantees this will be before October 17," he added.
Pinera said earlier this week he believed the 33 miners would be rescued before October 15. He is due to depart on a government visit to Europe on October 17, government officials said.
In his last visit to the mine on September 19, Pinera pledged to return the day the miners were extracted and personally hug each one.
Mines Minister Laurence Golborne said over the weekend that his best estimate was that the miners would be extracted in the second half of October.
Political opponents and even some relatives of the trapped miners have speculated in recent weeks that Pinera was trying to score political points from the miners' rescue. National opinion polls show his popularity has risen thanks to his handling of the accident.
Prior to the disaster his administration had been under political fire for the slow pace of government reconstruction after the February earthquake and tsunami along Chile's south and central coast, and for his handling of a hunger strike by members of the Mapuche indigenous group of southern Chile, who are fighting for independence.
Against the backdrop of political questioning, technical problems plagued the drilling effort at the San Jose mine.
The Strata 950 drill, dubbed Plan A, had reached 587 meters by 8 a.m. Tuesday. The men are nearly 700 meters (2,300 feet) underground, but could be rescued from different levels.
Andre Sougarret, mines manager for state-run copper company Codelco and on-site rescue coordinator, said that operation was stopped Tuesday while the drill head was changed. It was not expected to resume until late Wednesday.
It is currently making its first pass down with a 12.5-inch diameter hole to the roof of the 50-square-meter (500-square-foot) refuge at Level 100 (100 meters above sea level). It would have to make a second pass to widen that shaft to 28 inches.
The Schramm T-130 drill, so-called Plan B, was at 466 meters as of 8 a.m. Tuesday and is aiming for the roof of the mine workshop on Level 135 (135 meters above sea level). It had completed just two meters in the previous 24 hours.
Sougarret said the drill hammer had been swapped out but hit fresh problems after running into rock that was tougher than expected. He said the drill diameter would be reduced from 28 inches to 26 inches until the hammer had cleared the hard rock but added that the slightly smaller diameter would not cause problems for the rescue.
The Rig 421 oil drill, so-called Plan C, is currently at 265 meters and en route to the roof of the tunnel at Level 150 (150 meters above sea level). It is currently drilling a 17.5-inch diameter hole -- smaller than the 28 inches required to rescue the miners -- in an effort to realign after veering off course over the weekend.
Mine engineer Renee Aguilar, another of the rescue coordinators, said the first 10 members of a 16-strong extraction team arrived at the San Jose mine Tuesday.
The group consisted of Codelco rescue experts. Two other rescue experts from the northern Atacama region, along with three Navy and one police paramedic, were due to arrive at the mine later Tuesday.
Once the rescue shaft has been completed and the extraction begins, four members of the 16-person team will be chosen to descend into the mine to carry out final medical checks on the 33 miners. They will then enclose the miners, one-by-one, in a 21.5-inch diameter rescue cage that has been dubbed the "Phoenix capsule." Rescuers on the surface will winch them up.
Jean Romagnoli, sports medic and personal trainer working to get the miners in shape for their rescue, said the Phoenix capsule would be hoisted to the surface at a speed of about 60 kilometers per hour and would exert about 2 Gs of pressure on the miners.
He said small bio-metric monitors, mounted on chest belts, had been sent down to the miners to help keep track of their physical condition. He said the miners are working out for at least one hour a day to ensure they keep their weight down and can fit into the rescue capsule.
The U.S.-made monitors, known as Zephyr BioHarnesses, will record the miners' vital signs, pulse, heart rhythm and breathing. Romagnoli said similar monitors were used to check on the physical training of Chile's Davis Cup tennis stars.