The United States and South Korea will launch annual joint military exercises this month, officials said Tuesday, amid continued tensions with North Korea over two deadly border incidents last year.

The Key Resolve/Foal Eagle drills will start February 28 and involve 12,800 US troops, the Combined Forces Command (CFC) said. Some 200,000 South Korean troops will also take part, according to the defence ministry.

The North habitually criticises the drills as a preparation for invasion.

The allies as in previous years will test their ability to deal with "all possible contingencies" in the North beyond just a conventional attack on the South, Yonhap news agency quoted a military source as saying.

These reportedly include localised provocations, tracing weapons of mass destruction, a sudden regime change in the communist state and an exodus of refugees.

Leader Kim Jong-Il is preparing for an eventual power transfer to his youngest son Jong-Il.

A CFC spokesman declined to comment on possible scenarios.

US General Walter Sharp, who leads the combined forces, said in a statement the drills would practise responses "to a number of realistic scenarios beyond defeating a conventional attack".

The North's shelling of a South Korean border island last November killed four people including civilians and briefly sparked fears of war.

Seoul says Pyongyang also torpedoed one of its warships near the disputed Yellow Sea border last March, a charge it denies.

Inter-Korean military talks aimed at easing tensions broke down last week.

Key Resolve, a command post exercise involving computer simulation, will last until March 10. Part of Foal Eagle, a joint air, ground and naval training exercise, will continue through April 30.

Yonhap said that a US aircraft carrier group would take part for the first time in two years. A CFC spokesman declined to comment.

The United States has based troops in the South since the 1950-53 war and currently has 28,500 there.