More than 80 people have died after flash floods and landslides swept the East Nusa Tenggara province in southern Indonesia, an official said on Monday.

Josef Nae Soi, deputy governor of East Nusa Tenggara, told Anadolu Agency that 18 people died in Lembata regency and 60 others were killed in East Flores regency, while 100 are still missing in the incidents that occurred on Sunday.

-We don't know yet whether they [missing] fled to a relative's place or were buried- said Soi, adding that the death toll was expected to rise as evacuation efforts continue.

Floods and landslides triggered by tropical cyclone Seroja struck Indonesia's southern province after midnight, affecting the surrounded areas.

Soi said the city of Kupang was hit by floods and that a ship anchored in the harbor sank due to the high waves.

-So far, there have been no reports of casualties [in Kupang city]- he said on the phone.

Meanwhile, the Southeast Asian country's National Disaster Management Agency (BNPB) said that at least 475 families had been affected and 165 people displaced in East Sumba regency by the floods, which inundated four sub-districts.

The possibility of extreme weather conditions will remain in the area until April 9, according to the Meteorology, Climatology and Geophysics Agency (BMKG).