North Korea has completed deployment of about 50,000 special forces along the border with South Korea, a report said Wednesday, amid high tensions over the sinking of a Seoul warship.

The deployment began two or three years ago and seven 7,000-strong divisions are now in place, an unidentified senior government official told Yonhap news agency.

"The threat that North Korea may infiltrate special forces for limited warfare has become real," the agency quoted a separate senior defence ministry official as saying.

The defence ministry refused to confirm the Yonhap report, but President Lee Myung-Bak discussed the North's special warfare capabilities at an unprecedented meeting Tuesday with 150 top officers from all armed services.

At the meeting, Lee hinted strongly that the North was involved in the sinking of a South Korean warship with the loss of 46 lives near the disputed sea border on March 26.

Suspicions are growing that the 1,200-tonne ship was hit by a torpedo from the communist state, which has denied involvement.

Lee said the South must be better prepared to tackle "asymmetric" military threats including special warfare units.

A defence ministry report in 2008 said the North -- learning lessons from the Iraq war -- had strengthened its special warfare capability by augmenting light infantry units and enhancing their street warfare, night-time and mountaineering training.

The North has about 180,000 special forces, it said, adding they would be used for "multifarious types of attacks and mixed warfare" against the South.

earlier related report
N.Korea leader expected to meet with Chinese leaders: report
Beijing (AFP) May 5, 2010 - North Korea's leader Kim Jong-Il was expected to meet Chinese leaders Wednesday as he continued a secretive trip likely to focus on aid and efforts to halt Pyongyang's nuclear drive.

Kim's first trip in four years to China -- North Korea's sole major ally and its main source of finance, food and fuel -- is shrouded in mystery and has not been officially confirmed by either Beijing or Pyongyang.

The North Korean leader, who travelled to China on board an armoured train Monday and stopped off in the northeastern city of Dalian, was expected to meet China's President Hu Jintao Wednesday, South Korea's Yonhap news agency said.

The agency quoted diplomats as saying he would stay at Diaoyutai Guest House in Beijing before heading home Thursday.

The reclusive 68-year-old Kim, who is thought to have suffered a stroke in mid-2008, Tuesday reportedly inspected a port under construction outside Dalian -- a city seen as a model of China's economic development.

It was unclear when he was heading to Beijing but members of Kim's delegation checked out of their Dalian hotel late Tuesday, unnamed sources told Yonhap, prompting speculation he would travel to the capital overnight.

Analysts said China could use the trip to press Kim to return to six-party nuclear disarmament talks he quit in April last year in return for aid. The talks group the United States, China, Japan, Russia, North and South Korea.

The North 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.

But other analysts say the as-yet unexplained sinking of a South Korean warship in March -- which was ripped apart by an external blast, killing 46 sailors -- has made an early resumption of the six-party talks less likely.

Seoul has hinted the incident could be Pyongyang's fault. The North has denied all responsibility.

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.