South Korean troops launched a major exercise Monday to test their capability to mount beach assaults and landings, military officials said.

Thousands of troops including about 2,000 marines are taking part in the week-long exercise off the southeastern port of Pohang, the defence ministry said.

Anti-submarine aircraft and dozens of jet fighters, 15 navy ships and 21 armoured landing vehicles were also mobilised, a ministry spokesman said.

It was the South's first major joint landing drill involving naval, air force and marine forces since North Korea in November bombarded a frontline island near the disputed Yellow Sea border, killing two soldiers and two civilians.

Cross-border relations have been icy for more than a year, since the South accused the North of torpedoing a warship near the border in March 2010.

The North denies responsibility for the sinking, which killed 46 sailors.

South Korea has since then staged a series of drills alone or together with US troops as a show of strength against the North.

US and South Korean troops staged computerised joint war games and joint field training in March and April. On May 3 the South held live-fire artillery exercises on two frontline islands near the sea border.