Torrential rain Monday forced the Taiwanese city of Kaohsiung to shut schools and offices as floods overwhelmed its sewage system which was severely damaged by gas explosions last month that killed 30 people and injured 300.

Residents rushed to pile up sandbags in the two districts where drainage systems were affected by the blasts but many were marooned by the rising waters.

At least 180 mm (seven inches) of rain fell Monday morning following weekend downpours which dumped hundreds of millimetres of rain on the southern city.

"We've deployed dozens of water pumps in the two districts hoping they would help drain the water," a city government official said.

Around 360,000 people live in the two districts, accounting for around 13 percent of the population of Taiwan's second biggest city.

"The flooding over the past few days was caused by the serious damage caused to the sewage systems by the gas explosions," Kaohsiung Mayor Chen Chu said.

The July 31 explosions in underground industrial pipelines that cross the city sparked massive fires, leaving trenches running down the middle of some streets and throwing vehicles onto the roofs of buildings several stories high.

Reconstruction work has ground to a virtual standstill due to the flooding and the Central Weather Bureau warned of more downpours across southern Taiwan until Wednesday, raising fears of further floods.

One angry resident told Formosa TV that his home had been flooded several times since last week.

"This has never happened before," he said.

The government and local authorities dispute who bears responsibility for failing to monitor the safety of the pipelines that exploded, as well as who should shoulder the massive reconstruction costs.

The city blames Taiwanese company LCY Chemical Corp. for the blasts, saying around 10 tonnes of propene may have leaked from pipelines operated by the firm in the hours before the first blast.

Prosecutors have twice raided the offices of LCY Chemical as part of their investigation into the cause of the accident.

The incident has already brought down economic minister Chang Chia-juch.

Kaohsiung's deputy mayor and three other officials in the city government have also resigned, but have been asked to stay on until the disaster relief operations have been completed.

Kaohsiung lies adjacent to a huge petrochemical complex housing dozens of plants, and many pipelines run under the densely-packed city.

The explosions were the second disaster to strike Taiwan in just over a week, after a TransAsia Airways plane crashed with the loss of 48 lives on July 23.