US Vice-President Joe Biden plans to visit Asia in an effort to ease tension between China and its neighbours over disputed islands in the East China Sea, the White House has said.

Mr Biden will visit China, Japan and South Korea next week, officials said.

China has claimed an "air defence identification zone" over the islands, insisting that aircraft obey its rules or face "emergency defensive measures".

US Defence Secretary Chuck Hagel called the move "potentially destabilizing".