The Australian government has warned North Korea that South Korea cannot continue to ignore threats to its security as the communist state's deadly game of brinkmanship edged closer to armed conflict.

North Korea appeared to move a missile capable of hitting South Korea and Japan to its east coast on Thursday. The movement was detected by South Korean and US intelligence, South Korea's Yonhap news agency reported, citing military and government sources.

Earlier in the day the US announced it was speeding the deployment of an advanced missile defence system to Guam in the next few weeks, two years ahead of schedule, in what the Pentagon said was ''a precautionary move'' to protect US naval and air forces from the threat of a North Korean missile attack.

That in turn followed the North Korean army's claim that it had final approval to launch ''merciless'' military strikes on the US, involving the possible use of ''cutting-edge'' nuclear weapons.