(adds China border report, analyst)
SEOUL, Nov 13 (Reuters) - North Korea may be hoping to squeeze concessions from the international community by refusing to let inspectors remove samples from a plutonium-producing nuclear plant, the South's foreign minister said on Thursday.
South Korea's top nuclear envoy was quoted as saying the move was effectively a rejection of a promise North Korea made last month to allow for checks of its nuclear claims.
North Korea called the issue an infringement on its sovereignty, saying it was not part of a disarmament-for-aid deal struck with the United States, China, Japan, Russia and South Korea.
"If we consider North Korea's clear negotiation pattern, its strategy has always been to create a crisis before resolving something, and trying to use that point to secure further concessions," Foreign Minister Yu Myung-hwan told a seminar.
The North's statement came a little after Barack Obama met President George W. Bush at the White House and may serve as a reminder to the president-elect that Pyongyang, which uses its nuclear threat to get a seat at the table with world powers, does not want to be ignored by the new administration, analysts said.
"North Korea doesn't want to be the top policy concern of the U.S. administration because that is too dangerous. But it always wants to stay somewhere in the top five," a diplomatic source familiar with the North said.
North Korea reached a deal last month to resume disabling its Soviet-era Yongbyon nuclear plant and allow in inspectors to verify claims it made about its atomic arms programme after the United States removed it from a terrorism blacklist and rolled back trade sanctions.
The United States estimates the North has produced about 50 kg (110 lbs) of plutonium, enough for six to eight nuclear bombs.
In Washington on Wednesday, State Department spokesman Robert Wood said North Korea was obligated by "understandings" reached last month to allow such sampling.
Pyongyang has also threatened to close its land border with the South from next month, angered by the hardline approach of Seoul's conservative government over its nuclear weapons programme.
The South's Defence Ministry said on Thursday it had sent a message to the North expressing its concern over the move to stop the few exchanges that exist between the states divided since the Cold War.
North Korea has already begun restricting visitors from its main benefactor China, travel agents said, including virtually closing off one of its main land border crossings at Dandong.
Travel agents in China, who send a steady though small flow of tourists to North Korea, said they were still organising visits, though trips had to be made via air rather than by rail.
China's relations with North Korea have long been characterised as being "as close as lips and teeth" after they fought side-by-side during the 1950-53 Korean War.
Beijing had increased the number of troops on its border with North Korea to prevent against a possible flood of refugees flowing into its country if North Korean leader Kim Jong-il, though to have suffered a stroke in August, lost control of his state, the Financial Times on Thursday reported U.S. officials as saying.
Additional reporting by Arshad Mohammed in Washington and Ben Blanchard in Beijing, editing by Jonathan Thatcher and Sanjeev Miglani
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