Two US B-52 bombers flew over a disputed area of the East China Sea without notifying Beijing, despite China’s bid to create an expanded "air defense zone," US officials said Tuesday.

Two US B-52 bombers flew over a disputed area of the East China Sea without notifying Beijing, despite China's bid to create an expanded "air defense zone," US officials said Tuesday.

The unarmed aircraft took off from Guam on Monday and the flight was "long-planned" as part of a regular exercise in the area, a US defense official, who spoke on condition of anonymity, told AFP.