A multi-million-dollar lawsuit filed against Jakarta's governor over deadly New Year flooding was sidelined due to more floods.

Lawyers on their way to court were stymied as key roads were swamped following torrential rain that inundated neighbourhoods in Indonesia's capital and saw disaster officials comb districts in pontoon boats in search of at-risk residents.

"I spent hours trying to reach the court but all the roads were inundated," said lawyer Azas Tigor Nainggolan. "The hearing has been postponed because access to the court was flooded."

"This proves our point. The city administration is not working to solve this problem," he added.

Tuesday's court session was supposed to be the first in the lawsuit.

Nainggolan represents Jakarta residents who filed the claim in January alleging governor Anies Baswedan was responsible for failing to provide the megacity with a proper early-warning system and effective emergency measures to minimise deaths and financial losses.

The early January floods killed nearly 70 people and left thousands homeless as whole neighbourhoods in the capital - a megalopolis home to around 30 million people - were submerged.

More than 200 flood victims are seeking 43 billion rupiah (€2.7 million) in compensation but lawyer Nainggolan said the latest floods would up the damages demand to more than 1 trillion rupiah.

"People had to evacuate, children could not go to school," he said of the earlier floods.

"It's gone beyond financial losses."