The announcer said that the 69-year old had died of physical and mental over-work on his way to give "field guidance".
He had suffered a stroke in 2008, but appeared to have recovered. The reclusive state had begun the process of transferring power to his son Kim Jong-un, believed to be in his late 20s.
Kim Jong-un, the senior Kim Jong-il's youngest son, is seen as the leader-in-waiting after he was appointed to senior political and military posts in 2010.
Following are analyst views:
Cai jian, expert on Korea, Fudan university, Shanghai: "China's biggest worry will be over North Korea's stability, and China's aim will be to ensure the country remains stable."
"It seems that over the last year the succession plan in North Korea has been proceeding on track for Kim's son, but we will need at least another year to know whether this will be able to happen smoothly."
"This has really come out of the blue. It's not like it had been rumoured for a while giving everyone time to properly prepare."
"I think security will be stepped up in North Korea, and China is also likely to tighten security along the border."
"If his death leads to chaos, then we could see a flow of refugees across the border."
Uday Bhaskar, Director of Indian defence strategy think-tank national maritime foundation, New Delhi: "India has been watching North Korea closely in terms of the nexus between the country, China and Pakistan involving weapons of mass destruction and the transfer of that technology."
"The transition will have an impact on how India sees that nexus and how it might be affected, that will be most relevant.
"Of course it will be desirable for regional stability to have a smooth transfer of power."
Lee Cho-Won, professor of political and foreign affairs at Chungang University, Seoul": Seeing that he died suddenly in a train, it's very likely he died from a second stroke.
"This is a crisis for the North Korean regime, and it will be difficult for the North Korean authorities to pull off a sudden change in policies as they are in shock.
"The succession of power to Kim Jong-un is likely to take place as planned.
"Kim Jong-un will try to carry on his father's policies, including plans to build a strong and prosperous country by next year. This will be necessary for him to garner support if there is to be a power struggle."
Bae Sung-Young, market analyst, Hyundai Securities, Seoul:"The equity market will be under downward pressure for some time. The news comes at a time when financial market had already been in a fragile shape.
"The key focus will be how the succession proceeds. Kim Jong-il was in his late 30s when his father died, but Kim Jong-un is still pretty young, in his early 20s. It is hard to predict how things in North Korea will develop from here this time. And this is a risk factor, uncertainty that financial market participants do not like.
"For now, we are keeping an eye on foreign investor reactions and developments in North Korea."
Takao Hattori, senior investment strategist, Mitsubishi Ufj Morgan Stanley Securities, Tokyo: "In light of uncertainties about what would follow after his death and what implications it would have on Asia, the initial reaction is to seek safe-haven in the dollar, which is a key global settlement currency."
"The market was leaning towards dollar buying seasonally, given the year-end and also with the European crisis, and this preference for the dollar will strengthen further."
"Investors will seek safe assets, namely the dollar, and the yen will likely come under selling pressure, too, in a broad risk aversion."
Choi Chang-Ho, financial analyst, Shinhan Financial Corp, Seoul: "The death of Kim Jong-il definitely will have a significant impact on the South Korean economy and stock markets in general.
"But the degree of the impact is hard to measure since the news has just broken out. The most important factor to watch is how much foreign investors will offload money.
"Up until now, there is no significant short-selling in the stock markets. "
Naoki Murakami, chief economist, Monex Securities, Tokyo: "We're seeing some 'risk-off' moves in the market as some players are expecting future turmoil in North Korea. The transition of power hasn't proceeded enough so a period of power struggle is expected."
Lee Sun-Yeb, market analyst, Shinhan Securities, Seoul: "The equity market is reacting to the news, however I do not thinks negative impact will last long. North Korea was collected and calm enough to deliver the news via television. Although the successor is still young, succession has been established officially for some time. Kim has been sick for a while."
Yang Moo-Jin, professor, University of North Korean studies: "Chances that the North Korean military is attempting a coup are very low because North Korea has called itself a nation sharing a common destiny with Kim Jong-un.
"I think the collective leadership of the party, government and military will go on for a while, because Kim Jong-un is still young.
"Now, South Korea urgently needs to think of who in North Korea it has to deal with. South Korea doesn't want any instability in North Korea so will probably work to expand its cooperation efforts."
Chung Young-Tae, Korea Institute of National Unification: "This was probably from a second stroke. Kim Jong-il's death was somewhat expected.
"What happens from now is very important. Any prospect for a strong and prosperous country is now gone.
"Kim Jong-un is not yet the official heir, but the regime will move in the direction of Kim Jong-un taking center stage.
"There is a big possibility that a power struggle may happen.
"It's likely the military will support Kim Jong-un.
"Right now there will be control wielded over the people to keep them from descending into chaos in this tumultuous time.
June Park, senior economist at Meritz Securities: "This is definitely negative factor for markets with no detailed information on his death. It will drive the stock markets lower and the Korean won to depreciate sharply as geopolitical risks are rising and foreign investors could withdraw money out of South Korea."
COMMENTS (12)
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For Putin, Ahmadinejad, Bashar al Assad and others the death of North Korea's dictator is a welcome distraction from the scrutiny they were under lately. The Kim dynasty has been in power in North Korea since its founding in 1948. The death of Kim Jong-il will not mean the demise of 6 decades of autocracy. His successor, Kim Jong-un is too young to govern without advisors of his deceased father, who are no doubt die-hard regimists. As little is known about this young man, he will only show his real colours when he takes the helm in a few years. Still we shouldn't deny him the chance to embark on the right side of history one day.
bad year for dictators
@ Bangladeshi His family stayed in power the old fashion way -- they execute or imprison anyone who they consider a threat - they blame the outside World for all their problems - and they don't allow their people access to news that doesn't originate from the govt. What amazes me is that some people in Pakistan admire this guy who is considered the most evil dictator on the planet.
@Bangladeshi: It starts with things like banning foreign news channels.
The apple doesn't fall far from the tree -- the world won't miss this guy. In the afterlife I hope he and his father meet up with the thousands who died of famine under their harsh regimes.
In Kim we had a great friend,philosopher and guide. He was the undisputed leader of the 'poor and hungry people (with nuclear bomb)'. There should be a national mourning.
How can a nation support & admire a single man for decades? The dynastic politics in NK is different from the Dynastic politics of S.asia where we see change of leadership. But in NK the same KIM family is ruling since the 1950s. What is their military doing? How can a whole nation be brainwashed to the extent of unrelenting admiration for a single leader? It is a truly mind boggling scenario.
This has been a bad year for dictators and tyrants.
N also cause of humaliting pakistan and enhancing image of pakistan as Nuclear poliferation state............
@With Love: you are wrong. he was distant relative of missile technology
Such a sad day for pakistan... He was the father of pakistan's missile technology...