Emergency services in Colombia are continuing to search for more than 50 miners who have been trapped underground for almost three days.
The men were cut off at a depth of almost 2km (1.2 miles) after an explosion ripped through a coal mine in the country's north-west.
So far, 19 bodies have been recovered, many of them badly burned.
Attempts to locate the miners had to be suspended several times when methane gas built up in the tunnels.
Rescue workers at the San Fernando mine in Amaga, Antioquia province, said temperatures of up to 40C in the mine tunnels and debris from the explosion had been hampering their work.
Colombian president Alvaro Uribe told relatives of those trapped he felt helpless in the face of the slow pace of the rescue.
Disaster Prevention Administration Director Jhon Fredy Rendon said the chances of finding anyone alive were very slim.
"For one or more miners to survive, they would have to be in a portion of the tunnel which hasn't collapsed, in an air pocket with enough oxygen, untouched by the gases or the explosion," said Mr Rendon.
He said an examination of the recovered bodies showed the miners had died as a result of the shock wave which followed the blast.
An investigation has been launched to determine what caused the explosion.
On Friday, 1,000 people attended a funeral service in Amaga for nine of the miners whose bodies had been recovered.
Many of the families of those still missing are preparing for the worst: Byron Ossa, a relative of one of the missing miners, said hopes of finding his relative alive were fading, Reuters reported.
During his visit to the town on Saturday, President Uribe demanded a thorough investigation into the incident, which some experts say was caused by a methane explosion.
Mining minister Hernan Martinez said records showed the mine did not have a proper ventilation system or gas-detection devices, AP reported.
He said the mine would not reopen until the investigation into the causes of the blast had been completed.
But general manager for the mine Jorge Buitrago told AP that it complied with safety requirements for monitoring and controlling gases.
Colombia is one of the world's largest coal exporters.
It has the second-largest reserves in South America, after Brazil. According to the US Energy Information Administration, it was the fourth-largest coal exporter in the world in 2008.
Dozens of workers have been killed in explosions at mines, many of which are makeshift.
A methane gas explosion killed eight workers in a mine last year, also in Antioquia province.
In February 2007, a gas explosion at a mine in north-eastern Colombia killed more than 30 workers.
After the blast at the makeshift La Preciosa site, about 580km (360 miles) north of the capital, Bogota, authorities said they would step up their supervision of Colombia's mines.