The United States is likely to pursue a controversial military base relocation within Okinawa Island in an area larger than that publicly disclosed, according to an internal U.S. government document and a source familiar with the matter.

The 2008 document, a copy of which has been obtained by Kyodo News, shows a blueprint for building inland facilities in addition to the offshore airstrip specified under a Japan-U.S. accord for the relocation within the prefecture, which is opposed by local residents.

The revelation is expected to complicate the long-stalled issue of relocating the U.S. Marine Corps' Air Station Futenma from a crowded residential area in the city of Ginowan to the less populated coastal area of Henoko in Nago.