Kim Jong-il in rare talks with Russia

The meeting in Siberia is expected to focus on Pyongyang's nuclear programme, energy and food shortages in the North.

North Korea is in talks with Russian gas monopoly Gazprom about a pipeline through its territory to South Korea.

South Korea media reports that the deal could be worth up to $100m annually for the impoverished nation.

Analysts say the pipeline would provide Pyongyang with a source of income - from transit handling fees - and give the regime a stronger incentive for stability.

But a BBC correspondent in Seoul says it would also give Pyongyang de facto control over a key energy supply to the South, and without a major step forward in relations on the peninsula, that is likely to make some in Seoul very nervous.

South Korea's ambassador to Russia, Lee Yun-ho, said in a recent interview with Russian media that the "project could improve our relations with the [North]".

Kim arrived in his armoured train in the border town of Khasan in the Russian Far East on Saturday.

The itinerary for his visit, which is expected to last about a week, has largely been kept secret.

During his first few days in Russia, Kim is reported to have visited a dam north of Vladivostock, taken a swim in the waters of Lake Baikal, and toured a Soviet-era aviation plant.

The leader's visit comes amid severe economic hardship and reports of food shortages in North Korea.

Last week, Moscow announced it was providing 50,000 tons of wheat to Pyongyang.

Kim is also expected to seek Moscow's support help in trying to restart stalled talks on North Korea's nuclear programme.

In 2009, Pyongyang walked out of six-party talks with South Korea, the US, Japan, China and Russia, and conducted its second nuclear test soon after.

The North has however recently expressed a desire to return to talks.