A sinkhole that suddenly opened up on a road just northeast of Tokyo and swallowed a truck has captured national attention as the rescue operation of the driver has dragged on for days.

A sinkhole near Tokyo that swallowed a dump truck hole on Tuesday has now doubled in wide after combining with a second sinkhole as rescue workers continued their dig to reach the vehicle's driver.

Emergency workers have been hampered by unstable ground since Tuesday, when a truck and its driver were swallowed north of Tokyo.