The Australian understands the local shire has been asked to report back to Canberra on potential building sites on the tiny Australian territory as department officials brace for a continuing influx of asylum-seekers that some predict could increase the island's population from about 3000 to more than 12,000 by 2014.

The department wants to know where it can and should build houses for the increasing population of fly-in, fly-out immigration workers from the Australian mainland.

Locals sources told The Weekend Australian that senior officials from the Department of Immigration and Citizenship have told them it is necessary to research and prepare early for the possibility that the number of irregular maritime arrivals on the island could blow out from 1,809 Thursday to between 4,000 and 5,000 by 2014.

Immigration Minister Chris Evans discussed land availability when he met bureaucrats and the local shire on the island on January 22. But a spokesman for Senator Evans denied his own department was predicting the asylum-seeker population would more than double and the overall island population would climb to between 12,500 and 15,000 within four years.