BANGKOK (AP) — Rescue workers in Laos searched Monday for an alternative passage into a flooded cave where two people are believed to have been trapped for nearly two weeks after heavy rainfall flooded the main entrance, making it impassable.

READ MORE: Four men rescued from flooded Laos cave as search continues for 2 others

The two people remain unaccounted for since a search and rescue operation began last month in a rugged area of Xaisomboun province, about 120 kilometers (75 miles) north of the capital, Vientiane. Five of the seven people initially trapped inside the cave have been rescued.

Malaysian diver Lee Kian Lie, who is involved in the operation, said workers were pumping water out of the cave.

"We will go into the suspected area to continue the search if the water level is lowered," he told The Associated Press.

Another team of rescuers is also looking around the other side of the cave in hopes of finding a dry passage that could provide access to the area where the missing people are believed to be trapped, he said.

Rescue teams from Laos and neighboring Thailand have been working together for more than a week. They were joined by divers from countries including Finland, Malaysia, Japan, Indonesia, France and Australia.

Several of the rescuers previously took part in the complicated 2018 cave rescue in northern Thailand that saved 12 schoolboys and their soccer coach from a flooded cave.

Laos's Rescue Volunteer for People group posted on its Facebook page that heavy rain caused "massive amounts of water" to flow down into the area, forcing them to suspend operations on Sunday night.

Kengkaj Bongkawong, head of the Thai group Metta Tham Rescue Kalasin, said workers are also looking for air shafts from above that may provide access into the cave.

"The team and I have used a radar scanner and satellite images and many other things as a basis for our navigation of the mountain," he said.

In remarks on his Facebook page, Kengkaj warned that even if a suitable alternative entrance is found, "it's going to be a very tough job," with access difficult and the constant problem of continuing rain flooding the cave.

It would require not only pumping water out, but also installing equipment to keep ventilating the cave's air supply, he said.

Rescuers believe the two missing people are trapped deeper inside the cave than the location where the five survivors were originally found on Wednesday. But the passage into that area is said to be very narrow and heavily flooded.

The villagers reportedly entered the cave nearly two weeks ago to look for valuable minerals such as gold before being trapped by a flash flood that blocked their way out. One other villager escaped and alerted the authorities.

The first man was safely extracted on Friday, guided through a narrow flooded passage by an expert diver. The remaining four left the cave on Saturday after the water receded enough for them to walk out on their own, rescuers said.