|The North-South Korea clash appears to be one of the most serious border incidents since 1950s war [AFP]
North Korea and neighbouring South Korea have engaged in an exchange of cross-border artillery firing on the South Korean island of Yeonpyeong, which killed at least two South Korean soldiers, injured 20 others and set dozens of houses ablaze in the island.
Both countries have claimed the other triggered the clash, which appeared to be one of the most serious border incidents since the 1950-53 Korean War.
The fighting has prompted a global reaction as fears deepen over whether it could escalate to another all-out war between the two neighbours.
The White House condemned North Korea's artillery attack against Yeonpyeong as a violation of the 1953 pact that ended the Korean War.
"South Korea is our ally. It has been since the Korean war," Barack Obama, the president, told ABC News. "And we strongly affirm our commitment to defend South Korea as part of that alliance.
"We strongly condemn the attack and we are rallying the international community to put pressure on North Korea.
"I'm not going to speculate on military actions at this point."
China appealed for the six-party talks to resume after the new revelations, and expressed concern over Tuesday's clashes.
"We have taken note of the relevant report and we express concern over the situation," Hong Lei, a foreign ministry spokesman, said.
Australia called North Korea's shelling of the islands "outrageously provocative".
Kevin Rudd, the foreign minister, said China should try to calm North Korea.
"This is still a tense situation," Rudd told Sky News, condemning the artillery barrage.
"I believe it's important now for China to bring all of its influence to bear on North Korea."
Russia sees a 'colossal danger' if fighting escalates on the Korean peninsula, Sergei Lavrov, the country's foreign minister, said.
"It is necessary to immediately end all strikes. There is a colossal danger which must be avoided. Tensions in the region are growing," Lavrov told reporters.
"Those who started this bear a huge responsibility," he said. "What is happening requires consultations."
Japan's prime minister called on his government to prepare for "all eventualities" after the North-South Korea clashes.
"Firstly I asked our people to put an all-out effort in gathering information on this incident. And secondly I asked that they prepare for all eventualities. Those are the two orders I just gave out."
French Foreign Minister Michele Alliot-Marie slammed the North Korean shelling.
"I condemn firmly the artillery strikes from North Korea on the Yeonpyeong island [which] resulted in two deaths among South Korean military forces and several injured among the civilian population," Alliot-Marie said in a statement.
"France calls on North Korea to halt the provocation and refrain from any further acts that could worsen tensions in the region."
Ban Ki-moon, the UN secretary-general, said he was "deeply concerned" over the deadly North Korean attack, which he condemned and said was one of the most serious incidents since the Korean War ended.
"The attack was one of the gravest incidents since the end of the Korean War," the UN said in a statement.
"The secretary-general condemns the attack and calls for immediate restraint."
The United Nations Security Council could hold an emergency meeting in the next day or two over Tuesday's cross-border attacks, a French diplomatic source told reporters on Tuesday.
Asked whether the Security council would meet, the source said: "It is in the works for either today or tomorrow. We are for it and (planning) is ongoing".