|Kim Jong-un's reported visit is aimed at securing Chinese support for a possible succession [File: EPA]
Confusion surrounds the visit of a high-level North Korean delegation to China as South Korean media said the North's Kim Jong-il had crossed the border, contradicting earlier reports that his son, Kim Jong-un, had made a visit.
South Korean television quoted presidential and government sources as saying the 69-year-old leader had entered China by train on Friday morning.
Earlier, the same broadcasters reported it was Kim Jong-un who arrived by train in Tumen, in the northeastern Chinese province of Jilin. A presidential source would not confirm the later reports.
"It's not certain whether Kim Jong-Un accompanied his father or not," one official told the Yonhap news agency.
The visit would be Kim Jong-il's third to China inside the past 12 months.
Support for succession
North Korea is preparing for a third generation of Kim family rule, with the inexperienced Kim Jong-un poised to take over from his father as the country's next leader.
If Kim Jong-un's trip to China is confirmed, it would be widely seen as an attempt to secure support for his succession, as the North faces food shortages and international pressure to abandon its nuclear programme.
Kim Jong-il's more recent visit was in August, a trip that reportedly included a meeting with Hu Jintao, the Chinese president, and an appeal for diplomatic and financial support for the younger Kim's succession.
Kim Jong-un reportedly accompanied his father on the trip.
China's foreign ministry office that handles relations with North Korea told the Associated Press that they did not know anything about a Kim Jong-un visit. But in the past, the Chinese government has only confirmed visits by Kim's father once he has returned home.
Al Jazeera's Andrew Thomas, reporting from the Chinese capital, Beijing, said that if the trip is confirmed, the Chinese leadership would seek guarantees that a transfer of power will not destabilise the region.
"The government here would not want to see tensions further raised in the Korean peninsula, and they would also want to see North Korea attempt to engage more with the international community," he said.
Kim Jong-un, believed to be in his 20s, made his public debut in September last year after being promoted to four-star general and receiving the important position of vice-chairman of the country's ruling Workers' Party of Korea's central military commission.
Kim's reported trip on Friday also comes as the United States and other countries accuse the North of pushing ahead with its nuclear programme despite documented food shortages.
However, China is standing by the North by blocking the release of a report by UN experts accusing North Korea of violating UN sanctions that ban the export and import of ballistic missile and nuclear-related items as well as conventional arms and luxury goods.
North Korea relies on China for more than diplomatic support. Beijing is also a major supplier of food and other aid.
The UN says North Korea, which faces chronic food shortages, needs more than 474,000 tonnes of food aid to fend off disaster, and activists want the US and South Korea to override any political reasons for
But the pleas for aid come amid suspicions that Pyongyang is exaggerating shortages and seeking food donations in part so it can devote more resources to its campaign to build a prosperous society during the 2012 centennial of the birth of North Korea founder Kim Il Sung.
South Korea says it will resume large-scale aid only after North Korea apologises for last year's deadly sinking of a South Korean warship - which Seoul blames on a North Korean torpedo, as well as the North's attack on South Korea's Yeogpyong island.
North Korea suffered a famine in the 1990s that saw about a million of its 23m people starve, as natural disasters and decades-long mismanagement devastated its centrally controlled economy.
Source: Al Jazeera and agencies