Seoul  - North Korea warned Tuesday that talks on ending its nuclear weapons programme would break down if the United Nations imposes sanctions on it for a rocket launch it plans next month.

The Foreign Ministry in Pyongyang would see such sanctions as "hostile activity" and "a breach" of a 2005 six-nation agreement in which North Korea promised to dismantle its nuclear programme in return for aid.

If the agreement is broken, there is "no grounds for the six-party talks to exist any more," a ministry spokesman was quoted as saying by state-run media.

The six-nation talks involve North and South Korea, the United States, China, Japan and Russia. They began in 2003 but have been stalled since last year.

The US, South Korea, Japan and UN Secretary General Ban Ki-moon have all warned North Korea against its planned launch between April 4 to 8. Pyongyang has said it plans to put a communications satellite into orbit, but Washington, Seoul and Japan fear the launch is a cover to test-fire an intercontinental ballistic missile.

North Korea risks violating a 2006 UN Security Council resolution that prohibits it from conducting nuclear and missile tests, and South Korea said a launch would be taken before the council.

The US State Department said Wednesday that any launch would violate Security Council decisions.

"The UN Security Council made it clear that ballistic missile technology that is used for launching satellites or launching missiles is, in effect, the same and held North Korea to a commitment not to engage in ballistic missile testing," deputy spokesman Gordon Duguid said in Washington.

Duguid would not say whether Washington will seek additional sanctions if Pyongyang proceeds with the test.

"I'm not going to predict what our reaction would be to something that hasn't taken place yet," he said.

Meanwhile, in Beijing, Chinese and South Korean officials met to discuss how to respond to North Korea's planned rocket launch, the Chinese government and South Korean media said.

Wi Sung Lac, South Korea's chief envoy to the North Korean nuclear talks, said there were differences with the Chinese side.

"China agreed that there has to be a unified response to the North Korean long-range rocket launch issue," Wi was quoted as saying by the South Korean news agency Yonhap after meeting Chinese Vice Foreign Minister Wu Dawei.

However, Seoul and Beijing differ on what that response should be, Wi said.

The envoy said before the talks that their focus would be on measures to be taken before and after the planned launch.

Officials from South Korea, the US and Japan are also to discuss North Korea Friday in Washington, Japan's Kyodo News reported.

China has also urged all parties to "refrain from taking actions that may escalate tensions." (dpa)