A team of rebels search for and remove mines using metal probes and one or two metal detectors from an olive grove outside of the town of Kikla in the western mountains of Liyba. (William Booth/Washington Post)

First Milad Saadi and his men pray. Then they walk into a minefield.

Saadi carries a poker; it looks like a car antenna. The sappers have an old metal detector, the kind used to look for lost coins at the beach, but they don’t use it much; the batteries are weak.

They wear no body armor, no helmets. They dig in the dust with their hands.

Twenty paces from the roadside, they find their first land mine, then a second, a third. They twist off the plungers that would trigger the devices and toss the bland, beige, deadly disks into a blue bucket. The mines are the size of a doughnut.

In less than an hour, they have found 125 Brazilian-made T-AB-1 antipersonnel mines.

“Stick around, we will find a thousand in this field today,” said Bashir Ghourish, a member of the seven-man de-mining team from nearby Zintan.

As rebels slowly press toward Tripoli, they are discovering ever more extensive minefields laid by forces loyal to Libyan leader Moammar Gaddafi in and around civilian areas. The number of mines unearthed by the rebels is quickly growing from hundreds to thousands, as opposition fighters move into towns abandoned by retreating Gaddafi troops.

“Over the past weeks, NATO has witnessed an increase in indiscriminate mining and the escalating use of force by pro-Gaddafi forces” in both Brega, an oil port 482 miles east of Tripoli, and the western mountains, said a NATO official, speaking on the condition of anonymity because of alliance ground rules.

Opposition forces battling to enter the oil refinery at Brega have been slowed by mines. Col. Ahmed Bani, a spokesman for the rebel army, told reporters that rebels deactivated thousands of land mines last week to secure a possible route into Brega.

Rebel military commanders at Kabaw in the western mountains say that five days ago they watched Gaddafi troops laying mines around the towns of Ghazaya, Tikut and Ruwas near the Tunisian border.

“It feels like there are reports of new fields every week now,” said Sidney Kwiram, a consultant for Human Rights Watch in Libya.

“In each of the front lines we have visited around the country, the Gaddafi forces have used land mines near their troop positions,” Kwiram said. “These minefields may be flanking troop positions one day, but the next day they are the reason that civilians cannot return home.”

So far, six people have been wounded in mine blasts here in the western mountains when the vehicles they were riding in struck one of the devices. Three have been hospitalized.

Sappers working here in the Kiklah area found 1,500 mines in one field, 196 in another. On Thursday, they returned to a grove of olive trees and shuffled through the dust, searching the ground for disturbed dirt that would signal a buried mine.

The Gaddafi forces were barracked in a boy scout camp nearby, and mine team leader Saadi said the government soldiers had laid the mines to protect themselves from attack.

In two hours here, they found more than 300 antipersonnel mines and 18 Chinese-made Type-72SP anti-vehicle mines.

“It is part of Gaddafi’s scorched-earth strategy,” Saadi said. “A kid might step on it, an old man, an animal. Anything that moves. It is an unimaginable thing. It’s a war crime.”

Saadi held up one of the antipersonnel mines. “You see it is plastic, with the explosive inside? It would last in the ground for centuries.”

Saadi and his team display little of the boisterous bravado of the younger rebels.

“This is a job for old men, quiet and careful,” said Abdul Hakim, who usually teaches high-school Arabic.

“It is my duty to clear out these fields, for the children, for people, no matter even if it is dangerous,” Hakim said. “You have to calm down and take a deep breath, go slow, because you know, here your first mistake is your last mistake.”

Correspondent Michael Birnbaum in Berlin contributed to this report.