At least 15 people, mostly children, are missing and are likely to be dead after floods and landslides hit Indonesia's easternmost Papua region after torrential rain, a local official said on Monday.

Thirteen of the victims were children aged between eight and 17 years old, Alfredo Agustinus Rumbiak, the police chief of the remote Nduga region, told Reuters.

The children were heading home after playing volleyball and had attempted to cross a river when the floods happened, he said.

They initially took refuge on some big rocks, but the current was too strong and they were swept away. Also, some rocks fell and buried them, Rumbiak said.

Residents, police and military personnel, as well as the local disaster mitigation agency are continuing to search for the victims, Rumbiak said, but their efforts are being hampered by the difficult, mountainous terrain.

Authorities need a helicopter to get to the location, or face an eight-hour trek from the nearest town, Rumbiak said.

The rescue is also being complicated by the fact the area is categorised as a "red zone" in security terms, he added.

Papuan separatists have fought for independence since Papua came under Indonesian control following Dutch rule in a vote overseen by the United Nations in 1969.

Rumbiak said the location of the landslide was in the same area where a separatist group killed dozens of workers who built a bridge back in 2018.