By Ben Blanchard and Jeremy Laurence
BEIJING/SEOUL (Reuters) - Bitter rivals North and South Korea held a second round of "constructive and useful" dialogue on Wednesday as momentum builds for a resumption of six-party talks on dismantling Pyongyang's nuclear weapons program.
The nuclear envoys from the two Koreas met in Beijing for their second meeting in two months, amid a thaw in tensions on the divided peninsula after relations nose-dived last year to the lowest level in nearly two decades.
"We talked about nuclear issues, and this is part of our effort to resume six-party talks. We will continue to make these efforts in the future," the South's envoy Wi Sung-lac told reporters, according to the South's Yonhap news agency.
But the two failed to bridge their differences over the starting point for a new round of the six-party talks, which also involve China, the United States, Japan and Russia.
The North's Ri Yong-ho echoed remarks by Wi, saying the talks were "constructive and useful." He maintained, however, that six-party talks should be held without preconditions.
Seoul and Washington insist that Pyongyang must first halt its nuclear activities, including its uranium enrichment program, and allow the return of international nuclear inspectors before talks can restart.
Experts say the six-party process appears to be firmly back in the frame, but say it will be next year before the forum is reconvened.
"This is the beginning of what may well be a very long process," a diplomat based in Pyongyang told Reuters.
Ties between the two Koreas have deteriorated sharply since the six-party talks broke down over two years ago. The North has since conducted a nuclear and long-range missile test, and 10 months ago unveiled a uranium enrichment program which opens another path to make an atomic bomb.
Last year, Seoul also blamed the North for sinking one of its warships, an accusation Pygonyang rejects, and the secretive state carried out a first ever artillery attack on a civilian location on South Korean soil.
Under pressure from their main allies, Washington and Beijing, to calm tensions, the two Koreas have this year taken tentative steps to restart regional talks which offer the North economic aid in return for abandoning its nuclear ambitions.
In July, the two Koreas' nuclear envoys met for the first time in two years. That was followed by a top level meeting between American and North Korean officials a week later.
North Korea's leader Kim Jong-il has reached out to his old Cold War friends in Beijing and Moscow for help in getting the talks restarted, as U.N. sanctions have starved the country of economic activity and hard currency.
Kim has twice visited China this year and last month made his first visit first to Russia in nearly a decade. Pyongyang said on Wednesday it was sending its premier, Choe Yong Rim, to Beijing next week.
Analysts say the North is unlikely ever to give up its pursuit of nuclear weapons, as it sees an atomic bomb as the ultimate bargaining chip, as well as a deterrent against attack.
Experts say, however, the six-party talks still have an important purpose as they serve to contain the North's nuclear weapons program and prevent proliferation of technology to other countries such as Syria and Myanmar.
South Korean President Lee Myung-bak earlier said that giving up nuclear weapons program was a key first step toward eventual unification.
"The most important thing ... is to remove threats to peace on the Korean peninsula through denuclearization and to build mutual trust between the South and the North," Lee said in a speech after receiving a global leadership award in New York.
(Editing by Sanjeev Miglani)