Washington, Mar 23 (IANS): Beijing officials warned a US military aircraft during a routine East China Sea flyover telling the pilots that they were illegally operating in its airspace and ordering the American plane to leave, a top official said.

The pilots of the US Air Force B-1B Lancer bomber aircraft on Sunday responded to the Chinese air traffic controllers, saying that they were conducting routine operations in international airspace and did not deviate from their flight path, US Pacific Air Forces spokesman Major Phil Ventura told CNN on Wednesday.

The bombers had entered the Chinese Air Defence Identification Zone (ADIZ) in the East China Sea, which covers airspace and islands that are also claimed by Japan.

"Pacific Air Forces ... did not recognise the ADIZ when was announced in November 2013, and neither does not recognise it today," Ventura said.

"The ADIZ has not changed our operations".

The US plane was flying 70 nautical miles southwest of South Korea's Jeju Island.

The ADIZ declaration required airlines flying over the designated waters to first notify Chinese authorities before transiting, reports CNN.

The US and Japanese governments do not recognise China's claim on the area.

According to the US Air Force, the Guam-based B-1 bomber was conducting a series of training missions with Japanese and South Korean military aircraft.