The incident occurred a few hours after North Korea warned that relations with the South would face a "catastrophic impact" if South Korea continued to reject talks it brought to an end last month.
The first round of discussions in two years had ended without progress in September after Seoul demanded an apology from Pyongyang for sinking ROKS Cheonan last March, with the loss of 46 lives.
In an interview with the Financial Times, South Korean President Lee Myung-bak has called on North Korea to emulate China’s economic model, as only “common prosperity” and peace could lead to an eventual reunification.
“I would really like [North Korea’s] chairman Kim [Jong-il] to see a lot more of China, the China of today, witnessing with his own eyes the result of what can happen to a country’s prosperity when you open up to the world,” Mr Lee said.
Most South Koreans want reunification but many fear the potential costs of rebuilding the poor, starving country, estimated by the south’s government at about US$ 1,000 billion.
Peace, however, is as elusive as ever, with Mr Lee describing Pyongyang as a “belligerent” force after one of its submarines torpedoed a South Korean ship in March.
Nevertheless, “North Korea will change, albeit in a very slow fashion,” he said.