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 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 preemptive deterrence,” said Lee Chung-min of Yonsei University in Seoul.

A Foreign Ministry spokesman in Pyongyang said it had responded in “self-defence” and accused the South of firing shells into its waters near the disputed maritime border.

“The DPRK that sets store by the peace and stability of the Korean peninsula is now exercising superhuman self-control but the artillery pieces of the army of the DPRK, the defender of justice, remain ready to fire,” said the North’s KCNA news agency.

It said the South was driving the peninsula to the “brink of war” with “reckless military provocation” and by postponing humanitarian aid.

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 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.

The United States and Japan urged China to do more to rein in North Korea after the reclusive nation fired scores of artillery shells on Tuesday at a South Korean island near their sea border. China’s Foreign Ministry urged the two Koreas to show “calm and restraint” and engage in talks as quickly as possible to avoid an escalation of tensions.

“China takes this incident very seriously, and expresses pain and regret at the loss of life and property, and we feel anxious about developments,” said spokesman Hong Lei.

China has long propped up the Pyongyang leadership, worried a collapse of the North could bring instability to its own borders and also wary of a unified Korea that would be dominated by the United States, the key ally of the South.

The joint US-South Korea drill in the waters between the Korean peninsula and China will likely enrage Beijing, which has said previous such exercises are a threat to its security and to regional peace and stability.

“China will not welcome the US aircraft carrier joining the exercises, because that kind of move can escalate tensions and not relieve them,” said Xu Guangyu, a retired major-general in the People’s Liberation Army.

Seoul, a city of over 10 million, was bustling as normal yesterday.

“My house was burnt to the ground,” said Cho Soon-ae, 47, who was among 170 or so evacuated from Yeonpyeong yesterday.

Despite the rhetoric, regional powers made clear they were looking for a diplomatic way to calm things down.

US President Barack Obama said he was outraged and pressed the North to stop its provocative actions.

A number of analysts suspect Tuesday’s attack may have been an attempt by North Korean leader Kim jong-il to raise his bargaining position ahead of disarmament talks which he has used in the past to win concessions and aid from the outside world, in particular the United States.