SEOUL - SOUTH Korea's military will this month stage a major computer-simulated war game on deterring a possible attack from North Korea, officials said on Friday.

The four-day Taegeuk exercise from July 20 comes amid high international tensions over the communist state's missile launches and its May nuclear test.

North Korea regularly denounces such exercises as preparations for an invasion of the communist state.

But the Joint Chiefs of Staff (JCS) said the annual exercise, which began in 1995, is defensive in nature and involves only the command posts of South Korea's army, naval and air force.

The country's 655,000-strong military, backed up by a 28,500-strong US contingent, faces off against North Korea's 1.2 million-member armed forces.

Cross-border relations have been hostile for over a year, since Seoul's conservative government rolled back a 'sunshine' policy of aid and engagement with Pyongyang.

The North is also engaged in a standoff with the international community over its banned nuclear and ballistic missile programmes.

Last Saturday it test-fired seven missiles in an apparent show of defiance against tougher UN sanctions imposed for its nuclear test.

Seoul's intelligence service has also raised suspicions that the North or its sympathisers were behind a major cyber attack this week that shut down US and South Korean websites.

'The exercise is to cope with various circumstances' including a cyber attack from North Korea, a JCS spokesman told AFP, without disclosing details.

South Korea will launch an information security command on January 1, two years earlier than planned, to fend off cyber attacks on government and military IT networks.

Its military computer networks especially are under growing cyber attack. -- AFP