The driver of a truck that fell into a gaping sinkhole at a busy intersection in Saitama Prefecture, near Tokyo, two weeks ago is still missing.

The search for the driver remains suspended, though heavy machines were seen operating at the site of the sinkhole in the city of Yashio on Monday.

Firefighters resumed their search using heavy machinery the previous day, but they ceased the operation after about 30 minutes, due to fears that the ground could further collapse.

Authorities decided not to conduct further searches inside the sinkhole because of safety concerns. They are weighing other options to look for the driver, such as deploying rescue personnel into an underground sewage pipe.

Saitama prefectural officials said they are now capable of monitoring the inside of the pipe around the clock via two small holes -- each about 10 centimeters in diameter -- that workers opened from the ground surface.

Saitama Governor Ono Motohiro said the monitoring holes will help rescue workers understand the situation inside the sewage pipe, including the truck's cab believed to be stuck there.