SEOUL, Feb 9 (AFP) - Kim Jong-Il restated North Korea's goal of ridding the Korean peninsula of nuclear weapons and reportedly sent his top nuclear envoy to Beijing, amid a diplomatic drive to revive disarmament talks.

The North's leader made his remarks Monday to senior Chinese official Wang Jiarui, who was visiting Pyongyang to try to coax the North back to the six-nation talks which it angrily abandoned last April.

Kim "reiterated on Monday the country's persistent stance to realise the denuclearisation of the Korean Peninsula" during his meeting with Wang, according to China's official Xinhua new agency.

"The sincerity of relevant parties to resume the six-party talks is very important," it quoted Kim as saying.

The report did not indicate whether the North is about to end its boycott of the forum.

Its top nuclear negotiator Kim Kye-Gwan flew to Beijing Tuesday along with Wang, South Korea's Yonhap news agency reported from the Chinese capital.

Analysts said the North, hit by tougher United Nations sanctions for its 2009 missile launches and nuclear test, may be seeking a way to return to the talks which group the two Koreas, China, Russia, Japan and the United States.

Wang gave Kim a message from Chinese President Hu Jintao, who renewed an invitation to visit Beijing, Xinhua reported.

UN chief Ban Ki-moon's top political adviser Lynn Pascoe was due in Pyongyang Tuesday in another apparent attempt to press the North to restart the nuclear disarmament dialogue.

As conditions for a return, the North wants Washington to agree to hold formal peace talks and seeks a lifting of the UN sanctions.

In an apparent conciliatory gesture, Pyongyang on Saturday freed a US missionary who had crossed the border on a lone campaign to publicise rights abuses.

But the North Monday accused South Korea of plotting to topple Kim's regime and warned that it has a "secret strike force" to protect the country.

"We have world-level ultra-modern striking force and means for protecting security which have neither yet been mentioned nor opened to the public in total," a statement from two security ministries said without elaborating.

It criticised efforts by the South's military to defend the disputed Yellow Sea border -- where the North fired artillery salvoes late last month -- and complained about the growing scattering of anti-Kim propaganda leaflets by balloon.

By depicting external threats Kim's regime is trying to tighten its grip over society following a failed currency revaluation last November 30, said Kim Yong-Hyun, a professor at Seoul's Dongguk University.

"Its economy has not been in good shape since the currency revaluation and it also needs to break the deadlock in six-party talks," Kim told AFP. Otherwise, its rulers knew the country could become unstable.

Monday's statement also aims to press Seoul's conservative government to soften its policy, he said. The South has linked major aid to progress on nuclear disarmament. (By Jun Kwanwoo/ AFP)