SEOUL, South Korea — North Korea said Saturday that its nuclear weapons were not a bargaining chip to trade for economic concessions, warning that it would never negotiate with the United States as long as Washington maintained its hostile policy toward the North.

The statement was the latest in a series in which North Korea has appeared to harden its position on its nuclear weapons program. Since the United Nations Security Council imposed more sanctions to punish North Korea for its launching of a long-range rocket in December and its third nuclear test last month, the country has said it will no longer attend talks on dismantling its nuclear program.

North Korea previously quit multinational nuclear talks, but until recently it had also often said ridding the Korean Peninsula of nuclear weapons was its ultimate goal.

Many regional analysts and officials have suggested that North Korea might eventually give up its nuclear weapons for a package of economic and other incentives. The harsh language used by the North, some say, was just a ploy to maximize the price.