SEOUL North Koreans poured into the streets on Monday to mourn the death of leader Kim Jong-il and state media hailed his untested son as the "Great Successor" of the reclusive state whose atomic weapons ambitions are a major threat to the region. Earlier, a tearful North Korean television announcer, dressed in black and her voice quavering, said the 69-year old ruler died on Saturday of "physical and mental over-work" on a train on his way to give "field guidance" -- advice dispensed by the "Dear Leader" on trips to factories, farms and the military. This could be a turning point for North Korea William Hague, UK Foreign Minister World reactionDeath triggers swift reaction 
 
 Fears were compounded by unconfirmed reports from South Korean news agency Yonhap that the North had test-fired a missile off its eastern coast before the announcement of Kim Jong-il's death was made. Martin Dempsey, chairman of the U.S. military's Joint Chiefs of Staff, said the missile test had likely been planned before Kim's death and U.S. officials said the military had so far not raised alert levels for some 28,500 U.S. troops in South Korea. 'UTTER DESPAIR' 
 
 North Korea's official KCNA news agency lauded Kim's youngest son, Kim Jong-un as "the outstanding leader of our party, army and people." Images from inside the secretive state showed people in the streets of Pyongyang weeping at the news of his death. The state news agency said a funeral would be held in Pyongyang on 28 December and Kim Jong-un would head the funeral committee. Expressing grief at Kim's death, China's Foreign Ministry spokesman Ma Zhaoxu was quoted by Xinhua news agency as saying, "We are confident the North Korean people will be able to turn their anguish into strength and unify as one." While his father had 20 years as official heir, Kim Jong-un only became successor by taking on official titles last year, months after Kim Jong-il suffered a stroke around August 2008. Shortly after he came to power in 1994, a severe famine caused by ill-judged economic reforms and poor harvests left an estimated two million people dead. Millions of North Koreans were "engulfed in indescribable sadness", the KCNA state news agency said, as people wept openly in Pyongyang. He was educated in Switzerland, is aged in his late 20s and is believed to be Kim Jong-il's third son - born to Mr Kim's reportedly favourite wife, the late Ko Yong-hui. The KCNA later reported that he had died of a "severe myocardial infarction along with a heart attack" at 08:30 local time on Saturday (23:30 GMT Friday). South Korea, still technically at war with the North, placed its troops and all government workers on emergency alert, but said there were no signs of any unusual North Korean troop movements. China - North Korea's closest ally and biggest trading partner - expressed shock at the news of his death and pledged to continue making "active contributions to peace and stability on the Korean peninsula and in this region". His presumed successor, Kim Jong-un, is largely unknown outside the secretive state, and countries throughout the region are watching closely for any instability in the transition of power. So soon after Kim Jong-il has died, no leader will dare say that an alternative policy course is needed," Zhu said. Experts say Kim Jong-un has the intelligence and leadership skills to make him suited to succeed his father. Analysts say that with the process of transition from father to son incomplete, Mr Kim's death could herald "very unstable times" in North Korea.
– Kim Jong Il, North Korea's mercurial and enigmatic leader, has died at the age of 69, according to state television. His death was was announced today by a tearful announcer in black who said he had died from physical and mental over-work while on a train trip to a location outside Pyongyang, Reuters reports. A later report from state-run media said the "Dear Leader" had died of heart failure. Kim, revered as a man of almost superhuman talents by state-run media, but widely mocked in the West, inherited power after his father's death in 1994. His designated successor is believed to be his son, Kim Jong Un, who is still in his 20s. Asian stock markets fell on the news of his death and South Korea placed its military on alert. With the transition to power in North Korea incomplete, "very unstable times" times could lie ahead for the diplomatically isolated nation, an analyst tells the BBC.