SEOUL, Nov 29 (Reuters) - Eleven Chinese and Russian military aircraft entered South Korea's air defence identification zone on Friday over a period of four hours, prompting South Korea to launch fighter jets, South Korea's military said.

The Russian and Chinese aircraft entered the area in sequence, all exited without incident or intruding South Korea's airspace, the Joint Chiefs of Staff said in a message to reporters.

South Korea's military had identified the aircraft before they entered the zone and deployed air force jets which conducted tactical manoeuvres in response, it said.

Chinese and Russian aircraft have frequently entered the South Korean air defence zone in recent years before exiting without incident. The two countries do not recognise the South Korean air defence zone.

Air defence identification zones are declared by a number of countries to monitor and control aircraft approaching territorial airspace for national security purposes.

Photo from AP