UN chief Ban Ki-moon said Thursday he was "deeply concerned" by rising tensions on the Korean peninsula after Pyongyang said it had approved plans for nuclear strikes on US targets.

Speaking on a visit to Monaco, Ban also said he hoped North Korea would "as soon as possible" lift restrictions on South Korean workers at the Kaesong complex, the last real surviving point of contact between the two countries."I am deeply concerned and troubled by the rising tension on the Korean peninsula caused by the very negative inflammatory rhetoric coming from the Democratic People's Republic of Korea," he said.

"At this time, I think all the parties concerned in the Korean peninsula, in particular the Chinese government, can play a very important role to calm down the situation."The North Korean military said Thursday it had received final approval for military action against the United States in response to what it called provocative US use of nuclear-capable stealth bombers in war games with South Korea.

While few of the North's threats have been matched with action, reports said it appeared to have moved a medium-range missile capable of hitting targets in South Korea and Japan to its east coast.