JAKARTA, Indonesia -- A boat carrying foreign tourists sank in central Indonesia, leaving 15 people missing, officials said Sunday.

The boat was on its way from Lombok island to Komodo island carrying 20 foreign tourists, four Indonesian crewmen and an Indonesian guide when it sank at about 6 p.m. Saturday, said Budiawan, head of the search and rescue agency in Mataram, the provincial capital of West Nusatenggara.

Ten people, including at least six of the foreigners, were rescued, said Budiawan, who like many Indonesians uses a single name. Among those rescued were two people each from New Zealand and Spain, and one each from Britain and France. It was not immediately clear who the other four rescued people were.

However, Tempo.co, a news website for Indonesia's leading magazine, Tempo, reported that all 10 of those who were rescued were foreigners, including three New Zealanders, two people each from Germany, the Netherlands and Spain, and a French national.

Budiawan said a search for the missing was underway, involving at least four ships.

The boat sank off Sangeang Api, a volcanic island in Bima district off the eastern coast of Sumbawa island.

The cause of the sinking was not immediately clear, but the weather conditions were poor at the time, according to Budiawan. Tempo.co quoted Abdul Wahab, co-ordinator for the search and rescue agency in Bima, as saying the boat was believed to be leaking when it sank.

Sutriyanto, another search official in Bima, said the number of passengers onboard might have been higher, given the absence of a manifest.

Komodo is part of the Lesser Sunda chain of islands and forms part of Komodo National Park, which is known for its endangered Komodo dragons that can grow longer than 3 metres.