A US aircraft  carrier group set off for Korean waters on Wednesday, a day  after North Korea rained artillery shells on a South Korean  island, in a move likely to enrage Pyongyang and unsettle its  ally, China.     

South Korea said the bodies of two civilians were found on  the island after Tuesday's attack, which is likely to stir up  more resentment in the country against its prickly neighbour.

The nuclear-powered USS George Washington, which carries 75 warplanes and has a crew of over 6,000, left a naval base south of Tokyo and would join exercises with South Korea from  Sunday to the following Wednesday, US officials in Seoul  said.   

US Forces Korea said the exercise was defensive and had  been planned well before Tuesday's attack.

"An aircraft carrier is the most visible sign of power  projection there is ... you could see this as a form of  pre-emptive deterrence," said Lee Chung-min of Yonsei  University in Seoul.

A foreign ministry spokesman in Pyongyang said in a  statement it had responded in "self-defence" and accused the South of firing shells into its waters near a disputed  maritime border.   

North Korea said the South was driving the pensinula to the "brink of war" with "reckless military provocation" and by postponing humanitarian aid, the North's official KCNA news  agency said. It did not refer to the planned military drills.

The government in Seoul came under pressure for the military's slow response to the provocation, echoing similar  complaints made when a warship was sunk in March in the same  area, killing 46 sailors.

Defence Minister Kim Tae-young was grilled by lawmakers  who said the government should have taken quicker and stronger retaliatory measures against the North's provocation.

"I am sorry that the government has not carried out ruthless bombing through jet fighters during the North's second round of shelling," said Kim Jang-soo, a lawmaker of  ruling Grand National Party and a former defence minister.

Tuesday's attack was the heaviest in the region since the  Korean War ended in 1953, and marked the first civilian deaths  in  an assault since the bombing of a South Korean airliner in  1987.  - Reuters