Residents ride a motorbike on a flooded street in Jakarta, Indonesia. Landslides and floods triggered by torrential downpours have left dozens of people dead in and around Indonesia's capital, as rescuers struggled to search for people apparently buried under tons of mud. Picture: Tatan Syuflana/AP

Jakarta - Indonesia's weather modification operation to break up clouds before they reach the capital Jakarta and cause flooding has been successful, an official said Tuesday.

Floods and landslides that hit Jakarta and its satellite cities on New Year's Day killed at least 67 people and displaced more than 36,000 others, the National Disaster Management Agency said. 

Authorities started cloud-seeding operations by shooting salt flares at clouds on the Java Sea and the Sunda Strait to induce rain over waters off Java island on Friday.

"We managed to trigger rainfall in those areas, resulting in reduced precipitation in the greater Jakarta area in terms of its duration and intensity," said the head of the Agency for the Application and Assessment of Technology (BPPT), Hammam Riza.     

Two aircraft made 16 trips on Monday to disperse 26,600 kilograms of salt used to induce rain, he said, adding that the operation would continue as long as needed. 

"Clouds are still forming and rain will still be expected in the greater Jakarta area, but the intensity is too low to cause flooding," Hammam said. 

Heavy rain starting on New Year's Eve caused rivers to burst, sending brown floodwaters to residential areas in the densely populated metropolis, which is home to about 30 million people. 

More than 60 people were killed in Jakarta and its surrounding areas.

The country's weather agency said the New Year's rainfall was the most extreme seen since 1866. 

Floods and landslides are common in Indonesia during the rainy season.