North Korea's leader Kim Jong-Il was to continue his highly secretive visit to China on Tuesday, at a time of tensions over the sinking of a South Korean warship and his regime's nuclear ambitions.

The rare trip to North Korea's sole major ally has been seen by some analysts as a sign that stalled six-nation talks on dismantling Kim's nuclear programme could be reinvigorated.

But others say mystery over the warship's destruction in March -- an incident in which 46 sailors were killed -- clouds any hope for early dialogue.

It is Kim's first trip in more than four years to China, North Korea's main source of finance, food and fuel. The country is seen as one of the few able to levy pressure on Pyongyang's hardline regime.

Kim, who is said to dislike air travel, has visited China four times since 2000, each time by train. The last trip, in January 2006, was also shrouded in secrecy and only formally announced after it had ended.

Analysts said China could use the current trip to press the reclusive leader to return to the six-party nuclear disarmament talks he quit in April last year, in return for badly needed aid.

North Korea has suffered from persistent food shortages since the Soviet Union collapsed two decades ago.

But US and South Korean officials have indicated the talks cannot restart until suspicion is resolved about any North Korean involvement in the March 26 sinking of the Cheonan warship.

The Cheonan was ripped apart by an external explosion. The South has not so far directly accused the North over the incident, and Pyongyang has angrily denied responsibility.

On the latest trip Kim's 17-carriage train went to the eastern Chinese port city of Dalian on Monday, South Korea's Yonhap news agency reported, citing sources in Seoul and Beijing.

The agency quoted another source in Dalian as saying he had seen Kim at the city's five-star Furama Hotel, which had an entire wing reserved for the North Korean delegation until Tuesday evening.

Receptionists at the hotel would not comment when contacted by AFP, and it was unclear when and if Kim was heading to Beijing.

earlier related report
N.Korean leader on rare visit to China
Beijing (AFP) May 3, 2010 - North Korea's reclusive leader Kim Jong-Il arrived in China on Monday, officials said, at a time of tension over the sinking of a South Korean warship and his communist regime's nuclear ambitions.

Some analysts said the rare trip to North Korea's sole major ally could reinvigorate stalled six-nation talks on dismantling Kim's atomic programme. But mystery over the warship's destruction clouds any hopes for early dialogue.

"Kim arrived at about five this morning," said an official at the Friendship Bridge tourist site, at northeastern China's Dandong border crossing with North Korea.

"We received a notice from the Public Security Bureau and the army that we should shut down tourist operations in the morning," the official told AFP by telephone.

Rail officials in China's Liaoning province also confirmed that a special train from North Korea crossed into the country early on Monday, but the Chinese foreign ministry refused immediate comment.

It is Kim's first trip in more than four years to China, North Korea's main source of finance, food and fuel. The country is seen as one of the few able to apply pressure on Pyongyang's hardline regime.

Kim, who is said to dislike air travel, has visited China four times since 2000 by train. The last trip in January 2006 was shrouded in secrecy and only formally announced after it had ended.

His 17-carriage train was thought to have headed to the eastern Chinese port city of Dalian en route to Beijing, South Korea's Yonhap news agency said, citing sources in Seoul and Beijing.

The agency quoted another source in Dalian as saying he had seen Kim at the city's five-star Furama Hotel that had an entire wing reserved for the North Korean delegation until Tuesday evening.

Receptionists at the hotel refused to comment when contacted by AFP.

In a potential further indication that Kim was in Dalian, a photographer for Japan's Kyodo News was detained by police there for over an hour before being released, Yasushi Kato, bureau chief of the agency's Beijing office, told AFP.

He said he was still unclear about where the photographer was detained or why, but added he had been sent to cover Kim's visit.

Analysts said China could press the reclusive leader to return to the six-party nuclear disarmament talks it hosts in return for badly needed aid.

North Korea has suffered from persistent food shortages since the Soviet Union collapsed two decades ago. Ongoing shortages were further aggravated last November by a bungled currency reform.

Kim's visit comes after Chinese President Hu Jintao on Friday met South Korean President Lee Myung-Bak and with North Korea's number two leader Kim Yong-Nam on the sidelines of the World Expo in Shanghai.

"Kim will likely express his commitment to returning to six-party talks while leaving a date for the return up to host China," Yang Moo-Jin of Seoul's University of North Korean Studies told AFP.

"In return, Kim will receive economic aid from China."

North Korea had agreed in previous rounds of the dialogue -- which groups the two Koreas, China, Russia, the United States and Japan -- to end its nuclear weapons drive in return for security guarantees and fuel aid.

But it angrily quit the talks in April last year and vowed to restart production of weapons-grade plutonium, carrying out its second atomic weapons test the following month.

Pyongyang says it will not go back to the nuclear dialogue until UN sanctions are lifted, and until the United States makes a commitment to hold talks on a formal peace treaty.

But US and South Korean officials have indicated the talks cannot restart until suspicion is resolved about any North Korean involvement in the March 26 sinking of the Cheonan corvette, which claimed the lives of 46 sailors.

According to Yang at the Seoul university, Kim "will try to convince the Chinese leadership that South Korea fabricated the Cheonan incident to set up North Korea".

"If China is convinced, it will promise to cooperate with the North in the possible future UN handling of this case. Otherwise, China will take a prudent stance without siding with North Korea."

The Cheonan was ripped apart by an external explosion. The South has not so far directly accused the North over the incident, and Pyongyang has angrily denied responsibility.