A helicopter will depart for the site on Tuesday, the spokesman for the Berau District Disaster Mitigation Board, Rismansyah, said on Monday.
The decision to deploy the helicopter to conduct a search for the missing foreigners came after the search and rescue (SAR) team aboard a ship found it hard to find the four Italians due to bad weather, he said.
"The weather, which changes often, at the site has resulted in high waves that have hampered the search effort," he said.
Rismansyah added that six speedboats and a tugboat would also be involved in the search for the foreign nationals.
"The six speedboats will be helped by a tugboat from Berau Coal, which will comb the coasts of islands close to the Derawan island," he said.
The four missing foreign nationals have been identified as Michela (33), Alberto (36), and Daniele (36) of Italy and Vana Chris (29) of Belgium, Rismansyah said.
They have been missing since 07.10 p.m. on Saturday, he said.
Two other Italians, Valeria (34) and Mouruzio Rege (45), who were earlier reported missing, had gone for snorkeling.(*)