* North Korea to launch satellite between Dec. 10 and Dec. 22
* Second launch this year after April's failure
* Launch comes as S.Korea holds polls, Seoul says it is "grave provocation"
* Chinese Communist Party delegation held talks with N.Korean leader on Friday
By David Chance
SEOUL, Dec 1 (Reuters) - North Korea is to carry out its second rocket launch of 2012 as its youthful leader Kim Jong-un flexes his muscles a year after his father's death, in a move that will likely heighten diplomatic tensions and draw criticism from Washington.
North Korea's state news agency announced the decision to launch another space satellite on Saturday, just a day after Kim met a senior delegation from China's Communist Party in the North Korean capital of Pyongyang.
China, under new leadership, is North Korea's only major political backer and has continually urged peace on the Korean peninsula, where the North and South remain technically at war after an armistice, rather than a peace treaty, ended the 1950-53 conflict.
No comment on the planned launch was immediately available from Beijing's foreign ministry.
Seoul's foreign ministry said in a statement that the move was a "grave provocation". Japan's Kyodo news agency said Prime Minister Yoshihiko Noda had ordered ministries to be on alert for the launch.
"North Korea wants to tell China that it is an independent state by staging the rocket launch and it wants to see if the United States will drop its hostile policies," said Chang Yong-seok, a senior researcher at the Institute for Peace Affairs at Seoul National University.
North Korea is banned from conducting missile or nuclear-related activities under United Nations resolutions imposed after Pyongyang carried out nuclear tests, although it says its rockets are used to put satellites into orbit for peaceful purposes.
Washington and Seoul believe the isolated, impoverished state is testing long-range missile technology with the aim of developing an intercontinental ballistic missile capable of carrying a nuclear warhead.
Pyongyang's threats are aimed, in part, at winning concessions and aid from Washington, analysts say.
The failed April rocket launch took place to celebrate the 100th anniversary of the birth of North Korean founder Kim Il Sung and the latest test will take place close to the Dec. 17 date of the death of former leader Kim Jong-il.
It will also come as South Korea gears up for a Dec. 19 presidential election in a vote that pits a supporter of closer engagement with Pyongyang against the daughter of South Korean dictator Park Chung-hee.
The April test was condemned by the United Nations, although taking action against the North is hard as China refuses to endorse further sanctions against Pyongyang.
North Korea is already one of the most heavily sanctioned states on earth thanks to its nuclear programme.
Pyongyang has few tools to pressure the outside world to take it seriously due to its diplomatic isolation and its puny economy.
The state that Kim Jong-un inherited last December after the death of his father boasts a 1.2 million-strong military, but its population of 23 million, many malnourished, supports an economy worth just $40 billion annually in purchasing power parity terms, according to the U.S. Central Intelligence Agency.
"The North's calculation may be that they have little to lose by going ahead with it at this point," said Baek Seung-joo of the Korea Institute for Defense Analyses in Seoul.
Baek said the test planned for December would likely be no more successful in launching a satellite than the April one that crashed into the sea between China and North Korea after flying just 120 km.
"Kim Jong-un may be taking a big gamble trying to come back from the humiliating failure in April and in the process trying to raise the morale for the military," Baek said.
North Korea's space agency said on Saturday that it had worked on "improving the reliability and precision of the satellite and carrier rocket" since April's launch.