China's Premier Wen Jiabao confirmed Sunday that North Korean leader Kim Jong-Il is visiting China to study its dramatic economic development, South Korean officials said.

Wen expressed hope that Kim would use the knowledge to revive his own country's faltering economy, they said.

He made the comments to the South's President Lee Myung-Bak during a meeting on the sidelines of a tripartite summit in Tokyo with Japan, said Lee's spokesman Hong Sang-Pyo.

It was the first official confirmation of a visit which began on Friday when Kim's special train rolled across the border. Until now the trip has been shrouded in secrecy.

Wen said the visit was intended "to provide the North with an opportunity to understand China's economic development and use the understanding for its own development", Hong told South Korean reporters in Tokyo.

The premier also made it clear that China opposes a nuclear-armed North Korea and would work to create the environment for inter-Korean dialogue, the spokesman said.

The visit is Kim's third in just over a year to China, the impoverished North's sole major ally and economic benefactor. During the previous trip last August, President Hu Jintao urged Kim to open up his country's state-directed economy.

Kim's regime introduced limited reforms in 2005 but later rolled back most of them, apparently fearing that an economic opening-up would entail a loss of political control over the North's 24 million people.

But the economy is struggling amid severe shortages of power and raw materials and the country also suffers persistent severe food shortages.

UN agencies have said six million people need urgent food aid after a very cold winter. The United States will send a team to Pyongyang this week to evaluate its needs.

Overseas aid is waning due to irritation at the North's nuclear and missile development and international sanctions have been imposed to try to curb those programmes.

Six-party talks aimed at scrapping the nuclear programme in exchange for diplomatic and economic benefits have been stalled for more than two years.

Japan's Prime Minister Naoto Kan said after the Tokyo summit that he expressed concerns about North Korea's newly disclosed uranium enrichment programme, which potentially gives it a second way to build atomic weapons.

The leaders agreed on the importance of North Korea showing sincerity before the six-country talks can resume and agreed to press it to take appropriate action, Kan said.

Seoul, Washington and Tokyo want Pyongyang to show sincerity about nuclear disarmament and improve cross-border relations. These were strained by two deadly border incidents last year which South Korea blamed on the North.

Kim arrived by special train in the eastern Chinese city of Yangzhou, close to Shanghai, on Sunday evening, South Korea's Yonhap news agency reported.

A motorcade apparently carrying Kim and his 70-member entourage left the station and headed for a state guest house, it said, quoting unnamed sources.

Yonhap noted that Kim's father, then-president Kim Il-Sung who died in 1994, visited Yangzhou in 1991 to hold talks with the then-Chinese leader Jiang Zemin.

Kim's train crossed the border and arrived in China's Tumen city early Friday. On Saturday he and his entourage were said to have inspected a car factory in the northeastern city of Changchun.

Analysts said the 69-year-old's latest trip appears aimed at securing economic assistance or food aid and demonstrating his grip on power, despite preparations for an eventual handover to his youngest son Jong-Un.

The leader appears to have speeded up succession planning after suffering a stroke in August 2008.