A major operation to rescue 10 trapped Mexican coal miners was approaching a crucial moment on Saturday,
President Andres Manuel Lopez Obrador said, raising the hopes of desperate relatives.
More than 300 soldiers and other personnel, including six military scuba divers, have joined the rescue effort in the northern state of Coahuila following Wednesday's accident, the government said.
A camera was lowered into one of the mine shafts to evaluate the conditions inside, civil defense authorities said, but there was no news of significant developments as nightfall approached.
Five workers managed to escape from the crudely constructed mine in the initial aftermath of the disaster, but since then, no survivors have been found.
The focus has been on pumping out water from the mine in Agujita in the municipality of Sabinas to make it safe enough to enter.
Authorities said that the three mine shafts descended 60 meters (200 feet) and on Friday the floodwater inside was reported to be 30 meters deep.
A French company has provided equipment to assist in the task, she said, without naming the firm.
The arrival of more powerful pumping equipment was also a reason for optimism, Zogbi added.
Water was seen flowing from the mine through drainage channels, lifting the hopes of relatives who spent a third night waiting anxiously for news.