U.S. says 'seriously concerned' about North Korea's nuclear work

(Reuters) - The United States remain seriously concerned about North Korea's nuclear work which it said breached international agreements, it said on Wednesday, a day after the isolated Asian country said it had the power to deter a U.S. "nuclear threat." The Unites States said North Korea's graphite moderated reactor could enable it to produce additional plutonium for weapons in the near future, among other nuclear activities. "These activities are clear violations of multiple (U.N.) resolutions and must cease immediately," the United States said in a statement on the website of its mission in Vienna, the Austrian capital that is home to the International Atomic Energy Organisation. (Reporting by Shadia Nasralla; Editing by Robin Pomeroy)