A Japanese city on Tuesday reopened a busy street that collapsed into a giant sinkhole, with the efforts of workers who toiled around the clock for a week drawing praise on social media.

The gigantic sinkhole, measuring around 30 metres (98 feet) wide and 15 metres deep, appeared last Tuesday in a bustling business district in the southwestern city of Fukuoka, swallowing part of a five-lane street.

The sinkhole, apparently triggered by subway construction in the area, had exposed the support columns of nearby buildings at a traffic intersection.

Japanese workers toiled continuously for a week, dumping huge amounts of wet cement and sand into the gaping hole and fixing electricity, gas and water lines that had stopped following the accident.

The street reopened at 5 am Tuesday (2000 GMT Monday), Fukuoka Mayor Soichiro Takashima said in a statement, exactly a week after the ground began sinking.

"We're very sorry for causing great trouble," Takashima said, noting that a ban on access to surrounding buildings was lifted.

Miraculously, no one was hurt in the accident in Fukuoka, the biggest city on the southernmost main island of Kyushu.

Many on social media expressed amazement at the quick recovery.

"I'm surprised the road reopened in a week!," one Twitter user said.

"Impressive. That was fast," said another.